fix: inject MCP tools during delegation (fixes #4571 )

When an agent with MCP servers configured is used as a sub-agent via delegation, its MCP tools were not loaded because the Crew's _prepare_tools() is not called for the delegated-to agent. This fix adds _inject_mcp_tools() to agent/utils.py and calls it from prepare_tools(), which is invoked by both execute_task() and aexecute_task(). MCP tools are now loaded on-demand when the agent has mcps configured, with deduplication and graceful error handling. Also adds 11 tests covering: - MCP tool injection with/without mcps - Deduplication of existing tools - Graceful failure handling - prepare_tools integration - Full delegation flow Co-Authored-By: João <joao@crewai.com>
feat: migrate CLI http client from requests to httpx
2026-04-25 04:13:03 +00:00 · 2026-02-23 15:49:58 +00:00 · 2026-02-20 18:21:05 -05:00 · 2026-02-20 13:15:50 -05:00
22 changed files with 495 additions and 148 deletions
--- a/lib/crewai/pyproject.toml
+++ b/lib/crewai/pyproject.toml
@@ -38,6 +38,7 @@ dependencies = [
    "json5~=0.10.0",
    "portalocker~=2.7.0",
    "pydantic-settings~=2.10.1",
+    "httpx~=0.28.1",
    "mcp~=1.26.0",
    "uv~=0.9.13",
    "aiosqlite~=0.21.0",
--- a/lib/crewai/src/crewai/agent/utils.py
+++ b/lib/crewai/src/crewai/agent/utils.py
@@ -273,6 +273,46 @@ def save_last_messages(agent: Agent) -> None:
    agent._last_messages = sanitized_messages


+def _inject_mcp_tools(agent: Agent, tools: list[BaseTool]) -> list[BaseTool]:
+    """Inject MCP tools into the tools list if the agent has MCP servers configured.
+
+    This ensures MCP tools are available even when the agent is invoked
+    outside the normal Crew task-execution flow (e.g. via delegation).
+
+    Args:
+        agent: The agent instance that may have MCP servers configured.
+        tools: Current list of tools.
+
+    Returns:
+        Updated list of tools with MCP tools added (if any).
+    """
+    mcps = getattr(agent, "mcps", None)
+    if not mcps:
+        return tools
+
+    if not hasattr(agent, "get_mcp_tools"):
+        return tools
+
+    try:
+        mcp_tools = agent.get_mcp_tools(mcps=mcps)
+        if mcp_tools:
+            # Merge without duplicates based on tool name
+            existing_names = {tool.name for tool in tools}
+            for tool in mcp_tools:
+                if tool.name not in existing_names:
+                    tools.append(tool)
+                    existing_names.add(tool.name)
+    except Exception:
+        # Log but don't fail task execution if MCP tool loading fails
+        agent._logger.log(
+            "warning",
+            "Failed to load MCP tools during task execution",
+            color="yellow",
+        )
+
+    return tools
+
+
 def prepare_tools(
    agent: Agent, tools: list[BaseTool] | None, task: Task
 ) -> list[BaseTool]:
@@ -286,7 +326,13 @@ def prepare_tools(
    Returns:
        The list of tools to use.
    """
-    final_tools = tools or agent.tools or []
+    final_tools = list(tools or agent.tools or [])
+
+    # Inject MCP tools when the agent has MCP servers configured.
+    # This is needed for delegation scenarios where the Crew's
+    # _prepare_tools() is not called for the delegated-to agent.
+    final_tools = _inject_mcp_tools(agent, final_tools)
+
    agent.create_agent_executor(tools=final_tools, task=task)
    return final_tools

--- a/lib/crewai/src/crewai/agents/crew_agent_executor.py
+++ b/lib/crewai/src/crewai/agents/crew_agent_executor.py
@@ -6,8 +6,10 @@ and memory management.

 from __future__ import annotations

+import asyncio
 from collections.abc import Callable
 from concurrent.futures import ThreadPoolExecutor, as_completed
+import inspect
 import logging
 from typing import TYPE_CHECKING, Any, Literal, cast

@@ -736,7 +738,9 @@ class CrewAgentExecutor(CrewAgentExecutorMixin):
                ] = []
                for call_id, func_name, func_args in parsed_calls:
                    original_tool = original_tools_by_name.get(func_name)
-                    execution_plan.append((call_id, func_name, func_args, original_tool))
+                    execution_plan.append(
+                        (call_id, func_name, func_args, original_tool)
+                    )

                self._append_assistant_tool_calls_message(
                    [
@@ -746,7 +750,9 @@ class CrewAgentExecutor(CrewAgentExecutorMixin):
                )

                max_workers = min(8, len(execution_plan))
-                ordered_results: list[dict[str, Any] | None] = [None] * len(execution_plan)
+                ordered_results: list[dict[str, Any] | None] = [None] * len(
+                    execution_plan
+                )
                with ThreadPoolExecutor(max_workers=max_workers) as pool:
                    futures = {
                        pool.submit(
@@ -803,7 +809,7 @@ class CrewAgentExecutor(CrewAgentExecutorMixin):
            return tool_finish

        reasoning_prompt = self._i18n.slice("post_tool_reasoning")
-        reasoning_message: LLMMessage = {
+        reasoning_message = {
            "role": "user",
            "content": reasoning_prompt,
        }
@@ -908,9 +914,9 @@ class CrewAgentExecutor(CrewAgentExecutorMixin):
        elif (
            should_execute
            and original_tool
-            and getattr(original_tool, "max_usage_count", None) is not None
-            and getattr(original_tool, "current_usage_count", 0)
-            >= original_tool.max_usage_count
+            and (max_count := getattr(original_tool, "max_usage_count", None))
+            is not None
+            and getattr(original_tool, "current_usage_count", 0) >= max_count
        ):
            max_usage_reached = True

@@ -989,13 +995,17 @@ class CrewAgentExecutor(CrewAgentExecutorMixin):
                        and hasattr(original_tool, "cache_function")
                        and callable(original_tool.cache_function)
                    ):
-                        should_cache = original_tool.cache_function(args_dict, raw_result)
+                        should_cache = original_tool.cache_function(
+                            args_dict, raw_result
+                        )
                    if should_cache:
                        self.tools_handler.cache.add(
                            tool=func_name, input=input_str, output=raw_result
                        )

-                result = str(raw_result) if not isinstance(raw_result, str) else raw_result
+                result = (
+                    str(raw_result) if not isinstance(raw_result, str) else raw_result
+                )
            except Exception as e:
                result = f"Error executing tool: {e}"
                if self.task:
@@ -1490,7 +1500,9 @@ class CrewAgentExecutor(CrewAgentExecutorMixin):
            formatted_answer: Current agent response.
        """
        if self.step_callback:
-            self.step_callback(formatted_answer)
+            cb_result = self.step_callback(formatted_answer)
+            if inspect.iscoroutine(cb_result):
+                asyncio.run(cb_result)

    def _append_message(
        self, text: str, role: Literal["user", "assistant", "system"] = "assistant"
--- a/lib/crewai/src/crewai/cli/authentication/main.py
+++ b/lib/crewai/src/crewai/cli/authentication/main.py
@@ -2,8 +2,8 @@ import time
 from typing import TYPE_CHECKING, Any, TypeVar, cast
 import webbrowser

+import httpx
 from pydantic import BaseModel, Field
-import requests
 from rich.console import Console

 from crewai.cli.authentication.utils import validate_jwt_token
@@ -98,7 +98,7 @@ class AuthenticationCommand:
            "scope": " ".join(self.oauth2_provider.get_oauth_scopes()),
            "audience": self.oauth2_provider.get_audience(),
        }
-        response = requests.post(
+        response = httpx.post(
            url=self.oauth2_provider.get_authorize_url(),
            data=device_code_payload,
            timeout=20,
@@ -130,7 +130,7 @@ class AuthenticationCommand:

        attempts = 0
        while True and attempts < 10:
-            response = requests.post(
+            response = httpx.post(
                self.oauth2_provider.get_token_url(), data=token_payload, timeout=30
            )
            token_data = response.json()
@@ -149,7 +149,7 @@ class AuthenticationCommand:
                return

            if token_data["error"] not in ("authorization_pending", "slow_down"):
-                raise requests.HTTPError(
+                raise httpx.HTTPError(
                    token_data.get("error_description") or token_data.get("error")
                )

--- a/lib/crewai/src/crewai/cli/command.py
+++ b/lib/crewai/src/crewai/cli/command.py
@@ -1,5 +1,6 @@
-import requests
-from requests.exceptions import JSONDecodeError
+import json
+
+import httpx
 from rich.console import Console

 from crewai.cli.authentication.token import get_auth_token
@@ -30,16 +31,16 @@ class PlusAPIMixin:
            console.print("Run 'crewai login' to sign up/login.", style="bold green")
            raise SystemExit from None

-    def _validate_response(self, response: requests.Response) -> None:
+    def _validate_response(self, response: httpx.Response) -> None:
        """
        Handle and display error messages from API responses.

        Args:
-            response (requests.Response): The response from the Plus API
+            response (httpx.Response): The response from the Plus API
        """
        try:
            json_response = response.json()
-        except (JSONDecodeError, ValueError):
+        except (json.JSONDecodeError, ValueError):
            console.print(
                "Failed to parse response from Enterprise API failed. Details:",
                style="bold red",
@@ -62,7 +63,7 @@ class PlusAPIMixin:
                    )
            raise SystemExit

-        if not response.ok:
+        if not response.is_success:
            console.print(
                "Request to Enterprise API failed. Details:", style="bold red"
            )
--- a/lib/crewai/src/crewai/cli/enterprise/main.py
+++ b/lib/crewai/src/crewai/cli/enterprise/main.py
@@ -1,7 +1,7 @@
+import json
 from typing import Any, cast

-import requests
-from requests.exceptions import JSONDecodeError, RequestException
+import httpx
 from rich.console import Console

 from crewai.cli.authentication.main import Oauth2Settings, ProviderFactory
@@ -47,12 +47,12 @@ class EnterpriseConfigureCommand(BaseCommand):
                "User-Agent": f"CrewAI-CLI/{get_crewai_version()}",
                "X-Crewai-Version": get_crewai_version(),
            }
-            response = requests.get(oauth_endpoint, timeout=30, headers=headers)
+            response = httpx.get(oauth_endpoint, timeout=30, headers=headers)
            response.raise_for_status()

            try:
                oauth_config = response.json()
-            except JSONDecodeError as e:
+            except json.JSONDecodeError as e:
                raise ValueError(f"Invalid JSON response from {oauth_endpoint}") from e

            self._validate_oauth_config(oauth_config)
@@ -62,7 +62,7 @@ class EnterpriseConfigureCommand(BaseCommand):
            )
            return cast(dict[str, Any], oauth_config)

-        except RequestException as e:
+        except httpx.HTTPError as e:
            raise ValueError(f"Failed to connect to enterprise URL: {e!s}") from e
        except Exception as e:
            raise ValueError(f"Error fetching OAuth2 configuration: {e!s}") from e
--- a/lib/crewai/src/crewai/cli/organization/main.py
+++ b/lib/crewai/src/crewai/cli/organization/main.py
@@ -1,4 +1,4 @@
-from requests import HTTPError
+from httpx import HTTPStatusError
 from rich.console import Console
 from rich.table import Table

@@ -10,11 +10,11 @@ console = Console()


 class OrganizationCommand(BaseCommand, PlusAPIMixin):
-    def __init__(self):
+    def __init__(self) -> None:
        BaseCommand.__init__(self)
        PlusAPIMixin.__init__(self, telemetry=self._telemetry)

-    def list(self):
+    def list(self) -> None:
        try:
            response = self.plus_api_client.get_organizations()
            response.raise_for_status()
@@ -33,7 +33,7 @@ class OrganizationCommand(BaseCommand, PlusAPIMixin):
                table.add_row(org["name"], org["uuid"])

            console.print(table)
-        except HTTPError as e:
+        except HTTPStatusError as e:
            if e.response.status_code == 401:
                console.print(
                    "You are not logged in to any organization. Use 'crewai login' to login.",
@@ -50,7 +50,7 @@ class OrganizationCommand(BaseCommand, PlusAPIMixin):
            )
            raise SystemExit(1) from e

-    def switch(self, org_id):
+    def switch(self, org_id: str) -> None:
        try:
            response = self.plus_api_client.get_organizations()
            response.raise_for_status()
@@ -72,7 +72,7 @@ class OrganizationCommand(BaseCommand, PlusAPIMixin):
                f"Successfully switched to {org['name']} ({org['uuid']})",
                style="bold green",
            )
-        except HTTPError as e:
+        except HTTPStatusError as e:
            if e.response.status_code == 401:
                console.print(
                    "You are not logged in to any organization. Use 'crewai login' to login.",
@@ -87,7 +87,7 @@ class OrganizationCommand(BaseCommand, PlusAPIMixin):
            console.print(f"Failed to switch organization: {e!s}", style="bold red")
            raise SystemExit(1) from e

-    def current(self):
+    def current(self) -> None:
        settings = Settings()
        if settings.org_uuid:
            console.print(
--- a/lib/crewai/src/crewai/cli/plus_api.py
+++ b/lib/crewai/src/crewai/cli/plus_api.py
@@ -3,7 +3,6 @@ from typing import Any
 from urllib.parse import urljoin

 import httpx
-import requests

 from crewai.cli.config import Settings
 from crewai.cli.constants import DEFAULT_CREWAI_ENTERPRISE_URL
@@ -43,16 +42,16 @@ class PlusAPI:

    def _make_request(
        self, method: str, endpoint: str, **kwargs: Any
-    ) -> requests.Response:
+    ) -> httpx.Response:
        url = urljoin(self.base_url, endpoint)
-        session = requests.Session()
-        session.trust_env = False
-        return session.request(method, url, headers=self.headers, **kwargs)
+        verify = kwargs.pop("verify", True)
+        with httpx.Client(trust_env=False, verify=verify) as client:
+            return client.request(method, url, headers=self.headers, **kwargs)

-    def login_to_tool_repository(self) -> requests.Response:
+    def login_to_tool_repository(self) -> httpx.Response:
        return self._make_request("POST", f"{self.TOOLS_RESOURCE}/login")

-    def get_tool(self, handle: str) -> requests.Response:
+    def get_tool(self, handle: str) -> httpx.Response:
        return self._make_request("GET", f"{self.TOOLS_RESOURCE}/{handle}")

    async def get_agent(self, handle: str) -> httpx.Response:
@@ -68,7 +67,7 @@ class PlusAPI:
        description: str | None,
        encoded_file: str,
        available_exports: list[dict[str, Any]] | None = None,
-    ) -> requests.Response:
+    ) -> httpx.Response:
        params = {
            "handle": handle,
            "public": is_public,
@@ -79,54 +78,52 @@ class PlusAPI:
        }
        return self._make_request("POST", f"{self.TOOLS_RESOURCE}", json=params)

-    def deploy_by_name(self, project_name: str) -> requests.Response:
+    def deploy_by_name(self, project_name: str) -> httpx.Response:
        return self._make_request(
            "POST", f"{self.CREWS_RESOURCE}/by-name/{project_name}/deploy"
        )

-    def deploy_by_uuid(self, uuid: str) -> requests.Response:
+    def deploy_by_uuid(self, uuid: str) -> httpx.Response:
        return self._make_request("POST", f"{self.CREWS_RESOURCE}/{uuid}/deploy")

-    def crew_status_by_name(self, project_name: str) -> requests.Response:
+    def crew_status_by_name(self, project_name: str) -> httpx.Response:
        return self._make_request(
            "GET", f"{self.CREWS_RESOURCE}/by-name/{project_name}/status"
        )

-    def crew_status_by_uuid(self, uuid: str) -> requests.Response:
+    def crew_status_by_uuid(self, uuid: str) -> httpx.Response:
        return self._make_request("GET", f"{self.CREWS_RESOURCE}/{uuid}/status")

    def crew_by_name(
        self, project_name: str, log_type: str = "deployment"
-    ) -> requests.Response:
+    ) -> httpx.Response:
        return self._make_request(
            "GET", f"{self.CREWS_RESOURCE}/by-name/{project_name}/logs/{log_type}"
        )

-    def crew_by_uuid(
-        self, uuid: str, log_type: str = "deployment"
-    ) -> requests.Response:
+    def crew_by_uuid(self, uuid: str, log_type: str = "deployment") -> httpx.Response:
        return self._make_request(
            "GET", f"{self.CREWS_RESOURCE}/{uuid}/logs/{log_type}"
        )

-    def delete_crew_by_name(self, project_name: str) -> requests.Response:
+    def delete_crew_by_name(self, project_name: str) -> httpx.Response:
        return self._make_request(
            "DELETE", f"{self.CREWS_RESOURCE}/by-name/{project_name}"
        )

-    def delete_crew_by_uuid(self, uuid: str) -> requests.Response:
+    def delete_crew_by_uuid(self, uuid: str) -> httpx.Response:
        return self._make_request("DELETE", f"{self.CREWS_RESOURCE}/{uuid}")

-    def list_crews(self) -> requests.Response:
+    def list_crews(self) -> httpx.Response:
        return self._make_request("GET", self.CREWS_RESOURCE)

-    def create_crew(self, payload: dict[str, Any]) -> requests.Response:
+    def create_crew(self, payload: dict[str, Any]) -> httpx.Response:
        return self._make_request("POST", self.CREWS_RESOURCE, json=payload)

-    def get_organizations(self) -> requests.Response:
+    def get_organizations(self) -> httpx.Response:
        return self._make_request("GET", self.ORGANIZATIONS_RESOURCE)

-    def initialize_trace_batch(self, payload: dict[str, Any]) -> requests.Response:
+    def initialize_trace_batch(self, payload: dict[str, Any]) -> httpx.Response:
        return self._make_request(
            "POST",
            f"{self.TRACING_RESOURCE}/batches",
@@ -136,7 +133,7 @@ class PlusAPI:

    def initialize_ephemeral_trace_batch(
        self, payload: dict[str, Any]
-    ) -> requests.Response:
+    ) -> httpx.Response:
        return self._make_request(
            "POST",
            f"{self.EPHEMERAL_TRACING_RESOURCE}/batches",
@@ -145,7 +142,7 @@ class PlusAPI:

    def send_trace_events(
        self, trace_batch_id: str, payload: dict[str, Any]
-    ) -> requests.Response:
+    ) -> httpx.Response:
        return self._make_request(
            "POST",
            f"{self.TRACING_RESOURCE}/batches/{trace_batch_id}/events",
@@ -155,7 +152,7 @@ class PlusAPI:

    def send_ephemeral_trace_events(
        self, trace_batch_id: str, payload: dict[str, Any]
-    ) -> requests.Response:
+    ) -> httpx.Response:
        return self._make_request(
            "POST",
            f"{self.EPHEMERAL_TRACING_RESOURCE}/batches/{trace_batch_id}/events",
@@ -165,7 +162,7 @@ class PlusAPI:

    def finalize_trace_batch(
        self, trace_batch_id: str, payload: dict[str, Any]
-    ) -> requests.Response:
+    ) -> httpx.Response:
        return self._make_request(
            "PATCH",
            f"{self.TRACING_RESOURCE}/batches/{trace_batch_id}/finalize",
@@ -175,7 +172,7 @@ class PlusAPI:

    def finalize_ephemeral_trace_batch(
        self, trace_batch_id: str, payload: dict[str, Any]
-    ) -> requests.Response:
+    ) -> httpx.Response:
        return self._make_request(
            "PATCH",
            f"{self.EPHEMERAL_TRACING_RESOURCE}/batches/{trace_batch_id}/finalize",
@@ -185,7 +182,7 @@ class PlusAPI:

    def mark_trace_batch_as_failed(
        self, trace_batch_id: str, error_message: str
-    ) -> requests.Response:
+    ) -> httpx.Response:
        return self._make_request(
            "PATCH",
            f"{self.TRACING_RESOURCE}/batches/{trace_batch_id}",
@@ -193,13 +190,11 @@ class PlusAPI:
            timeout=30,
        )

-    def get_triggers(self) -> requests.Response:
+    def get_triggers(self) -> httpx.Response:
        """Get all available triggers from integrations."""
        return self._make_request("GET", f"{self.INTEGRATIONS_RESOURCE}/apps")

-    def get_trigger_payload(
-        self, app_slug: str, trigger_slug: str
-    ) -> requests.Response:
+    def get_trigger_payload(self, app_slug: str, trigger_slug: str) -> httpx.Response:
        """Get sample payload for a specific trigger."""
        return self._make_request(
            "GET", f"{self.INTEGRATIONS_RESOURCE}/{app_slug}/{trigger_slug}/payload"
--- a/lib/crewai/src/crewai/cli/provider.py
+++ b/lib/crewai/src/crewai/cli/provider.py
@@ -8,7 +8,7 @@ from typing import Any

 import certifi
 import click
-import requests
+import httpx

 from crewai.cli.constants import JSON_URL, MODELS, PROVIDERS

@@ -165,20 +165,20 @@ def fetch_provider_data(cache_file: Path) -> dict[str, Any] | None:
    ssl_config = os.environ["SSL_CERT_FILE"] = certifi.where()

    try:
-        response = requests.get(JSON_URL, stream=True, timeout=60, verify=ssl_config)
-        response.raise_for_status()
-        data = download_data(response)
-        with open(cache_file, "w") as f:
-            json.dump(data, f)
-        return data
-    except requests.RequestException as e:
+        with httpx.stream("GET", JSON_URL, timeout=60, verify=ssl_config) as response:
+            response.raise_for_status()
+            data = download_data(response)
+            with open(cache_file, "w") as f:
+                json.dump(data, f)
+            return data
+    except httpx.HTTPError as e:
        click.secho(f"Error fetching provider data: {e}", fg="red")
    except json.JSONDecodeError:
        click.secho("Error parsing provider data. Invalid JSON format.", fg="red")
    return None


-def download_data(response: requests.Response) -> dict[str, Any]:
+def download_data(response: httpx.Response) -> dict[str, Any]:
    """Downloads data from a given HTTP response and returns the JSON content.

    Args:
@@ -194,7 +194,7 @@ def download_data(response: requests.Response) -> dict[str, Any]:
    with click.progressbar(
        length=total_size, label="Downloading", show_pos=True
    ) as bar:
-        for chunk in response.iter_content(block_size):
+        for chunk in response.iter_bytes(block_size):
            if chunk:
                data_chunks.append(chunk)
                bar.update(len(chunk))
--- a/lib/crewai/src/crewai/experimental/agent_executor.py
+++ b/lib/crewai/src/crewai/experimental/agent_executor.py
@@ -1,8 +1,10 @@
 from __future__ import annotations

+import asyncio
 from collections.abc import Callable, Coroutine
 from concurrent.futures import ThreadPoolExecutor, as_completed
 from datetime import datetime
+import inspect
 import json
 import threading
 from typing import TYPE_CHECKING, Any, Literal, cast
@@ -778,7 +780,7 @@ class AgentExecutor(Flow[AgentReActState], CrewAgentExecutorMixin):
            from_cache = cast(bool, execution_result["from_cache"])
            original_tool = execution_result["original_tool"]

-            tool_message: LLMMessage = {
+            tool_message = {
                "role": "tool",
                "tool_call_id": call_id,
                "name": func_name,
@@ -1358,7 +1360,9 @@ class AgentExecutor(Flow[AgentReActState], CrewAgentExecutorMixin):
            formatted_answer: Current agent response.
        """
        if self.step_callback:
-            self.step_callback(formatted_answer)
+            cb_result = self.step_callback(formatted_answer)
+            if inspect.iscoroutine(cb_result):
+                asyncio.run(cb_result)

    def _append_message_to_state(
        self, text: str, role: Literal["user", "assistant", "system"] = "assistant"
--- a/lib/crewai/src/crewai/task.py
+++ b/lib/crewai/src/crewai/task.py
@@ -1,5 +1,6 @@
 from __future__ import annotations

+import asyncio
 from concurrent.futures import Future
 from copy import copy as shallow_copy
 import datetime
@@ -624,11 +625,15 @@ class Task(BaseModel):
            self.end_time = datetime.datetime.now()

            if self.callback:
-                self.callback(self.output)
+                cb_result = self.callback(self.output)
+                if inspect.isawaitable(cb_result):
+                    await cb_result

            crew = self.agent.crew  # type: ignore[union-attr]
            if crew and crew.task_callback and crew.task_callback != self.callback:
-                crew.task_callback(self.output)
+                cb_result = crew.task_callback(self.output)
+                if inspect.isawaitable(cb_result):
+                    await cb_result

            if self.output_file:
                content = (
@@ -722,11 +727,15 @@ class Task(BaseModel):
            self.end_time = datetime.datetime.now()

            if self.callback:
-                self.callback(self.output)
+                cb_result = self.callback(self.output)
+                if inspect.iscoroutine(cb_result):
+                    asyncio.run(cb_result)

            crew = self.agent.crew  # type: ignore[union-attr]
            if crew and crew.task_callback and crew.task_callback != self.callback:
-                crew.task_callback(self.output)
+                cb_result = crew.task_callback(self.output)
+                if inspect.iscoroutine(cb_result):
+                    asyncio.run(cb_result)

            if self.output_file:
                content = (
--- a/lib/crewai/src/crewai/utilities/agent_utils.py
+++ b/lib/crewai/src/crewai/utilities/agent_utils.py
@@ -3,6 +3,7 @@ from __future__ import annotations
 import asyncio
 from collections.abc import Callable, Sequence
 import concurrent.futures
+import inspect
 import json
 import re
 from typing import TYPE_CHECKING, Any, Final, Literal, TypedDict
@@ -501,7 +502,9 @@ def handle_agent_action_core(
        - TODO: Remove messages parameter and its usage.
    """
    if step_callback:
-        step_callback(tool_result)
+        cb_result = step_callback(tool_result)
+        if inspect.iscoroutine(cb_result):
+            asyncio.run(cb_result)

    formatted_answer.text += f"\nObservation: {tool_result.result}"
    formatted_answer.result = tool_result.result
--- a/lib/crewai/tests/agents/test_async_agent_executor.py
+++ b/lib/crewai/tests/agents/test_async_agent_executor.py
@@ -2,7 +2,7 @@

 import asyncio
 from typing import Any
-from unittest.mock import AsyncMock, MagicMock, patch
+from unittest.mock import AsyncMock, MagicMock, Mock, patch

 import pytest

@@ -291,6 +291,46 @@ class TestAsyncAgentExecutor:
        assert max_concurrent > 1, f"Expected concurrent execution, max concurrent was {max_concurrent}"


+class TestInvokeStepCallback:
+    """Tests for _invoke_step_callback with sync and async callbacks."""
+
+    def test_invoke_step_callback_with_sync_callback(
+        self, executor: CrewAgentExecutor
+    ) -> None:
+        """Test that a sync step callback is called normally."""
+        callback = Mock()
+        executor.step_callback = callback
+        answer = AgentFinish(thought="thinking", output="test", text="final")
+
+        executor._invoke_step_callback(answer)
+
+        callback.assert_called_once_with(answer)
+
+    def test_invoke_step_callback_with_async_callback(
+        self, executor: CrewAgentExecutor
+    ) -> None:
+        """Test that an async step callback is awaited via asyncio.run."""
+        async_callback = AsyncMock()
+        executor.step_callback = async_callback
+        answer = AgentFinish(thought="thinking", output="test", text="final")
+
+        with patch("crewai.agents.crew_agent_executor.asyncio.run") as mock_run:
+            executor._invoke_step_callback(answer)
+
+            async_callback.assert_called_once_with(answer)
+            mock_run.assert_called_once()
+
+    def test_invoke_step_callback_with_none(
+        self, executor: CrewAgentExecutor
+    ) -> None:
+        """Test that no error is raised when step_callback is None."""
+        executor.step_callback = None
+        answer = AgentFinish(thought="thinking", output="test", text="final")
+
+        # Should not raise
+        executor._invoke_step_callback(answer)
+
+
 class TestAsyncLLMResponseHelper:
    """Tests for aget_llm_response helper function."""

--- a/lib/crewai/tests/cli/authentication/test_auth_main.py
+++ b/lib/crewai/tests/cli/authentication/test_auth_main.py
@@ -2,7 +2,7 @@ from datetime import datetime, timedelta
 from unittest.mock import MagicMock, call, patch

 import pytest
-import requests
+import httpx
 from crewai.cli.authentication.main import AuthenticationCommand
 from crewai.cli.constants import (
    CREWAI_ENTERPRISE_DEFAULT_OAUTH2_AUDIENCE,
@@ -220,7 +220,7 @@ class TestAuthenticationCommand:
        ]
        mock_console_print.assert_has_calls(expected_calls)

-    @patch("requests.post")
+    @patch("crewai.cli.authentication.main.httpx.post")
    def test_get_device_code(self, mock_post):
        mock_response = MagicMock()
        mock_response.json.return_value = {
@@ -256,7 +256,7 @@ class TestAuthenticationCommand:
            "verification_uri_complete": "https://example.com/auth",
        }

-    @patch("requests.post")
+    @patch("crewai.cli.authentication.main.httpx.post")
    @patch("crewai.cli.authentication.main.console.print")
    def test_poll_for_token_success(self, mock_console_print, mock_post):
        mock_response_success = MagicMock()
@@ -305,7 +305,7 @@ class TestAuthenticationCommand:
            ]
            mock_console_print.assert_has_calls(expected_calls)

-    @patch("requests.post")
+    @patch("crewai.cli.authentication.main.httpx.post")
    @patch("crewai.cli.authentication.main.console.print")
    def test_poll_for_token_timeout(self, mock_console_print, mock_post):
        mock_response_pending = MagicMock()
@@ -324,7 +324,7 @@ class TestAuthenticationCommand:
            "Timeout: Failed to get the token. Please try again.", style="bold red"
        )

-    @patch("requests.post")
+    @patch("crewai.cli.authentication.main.httpx.post")
    def test_poll_for_token_error(self, mock_post):
        """Test the method to poll for token (error path)."""
        # Setup mock to return error
@@ -338,5 +338,5 @@ class TestAuthenticationCommand:

        device_code_data = {"device_code": "test_device_code", "interval": 1}

-        with pytest.raises(requests.HTTPError):
+        with pytest.raises(httpx.HTTPError):
            self.auth_command._poll_for_token(device_code_data)
--- a/lib/crewai/tests/cli/deploy/test_deploy_main.py
+++ b/lib/crewai/tests/cli/deploy/test_deploy_main.py
@@ -4,10 +4,11 @@ from io import StringIO
 from unittest.mock import MagicMock, Mock, patch

 import pytest
-import requests
+import json
+
+import httpx
 from crewai.cli.deploy.main import DeployCommand
 from crewai.cli.utils import parse_toml
-from requests.exceptions import JSONDecodeError


 class TestDeployCommand(unittest.TestCase):
@@ -37,18 +38,18 @@ class TestDeployCommand(unittest.TestCase):
            DeployCommand()

    def test_validate_response_successful_response(self):
-        mock_response = Mock(spec=requests.Response)
+        mock_response = Mock(spec=httpx.Response)
        mock_response.json.return_value = {"message": "Success"}
        mock_response.status_code = 200
-        mock_response.ok = True
+        mock_response.is_success = True

        with patch("sys.stdout", new=StringIO()) as fake_out:
            self.deploy_command._validate_response(mock_response)
            assert fake_out.getvalue() == ""

    def test_validate_response_json_decode_error(self):
-        mock_response = Mock(spec=requests.Response)
-        mock_response.json.side_effect = JSONDecodeError("Decode error", "", 0)
+        mock_response = Mock(spec=httpx.Response)
+        mock_response.json.side_effect = json.JSONDecodeError("Decode error", "", 0)
        mock_response.status_code = 500
        mock_response.content = b"Invalid JSON"

@@ -64,13 +65,13 @@ class TestDeployCommand(unittest.TestCase):
            assert "Response:\nInvalid JSON" in output

    def test_validate_response_422_error(self):
-        mock_response = Mock(spec=requests.Response)
+        mock_response = Mock(spec=httpx.Response)
        mock_response.json.return_value = {
            "field1": ["Error message 1"],
            "field2": ["Error message 2"],
        }
        mock_response.status_code = 422
-        mock_response.ok = False
+        mock_response.is_success = False

        with patch("sys.stdout", new=StringIO()) as fake_out:
            with pytest.raises(SystemExit):
@@ -84,10 +85,10 @@ class TestDeployCommand(unittest.TestCase):
            assert "Field2 Error message 2" in output

    def test_validate_response_other_error(self):
-        mock_response = Mock(spec=requests.Response)
+        mock_response = Mock(spec=httpx.Response)
        mock_response.json.return_value = {"error": "Something went wrong"}
        mock_response.status_code = 500
-        mock_response.ok = False
+        mock_response.is_success = False

        with patch("sys.stdout", new=StringIO()) as fake_out:
            with pytest.raises(SystemExit):
--- a/lib/crewai/tests/cli/enterprise/test_main.py
+++ b/lib/crewai/tests/cli/enterprise/test_main.py
@@ -3,8 +3,9 @@ import unittest
 from pathlib import Path
 from unittest.mock import Mock, patch

-import requests
-from requests.exceptions import JSONDecodeError
+import json
+
+import httpx

 from crewai.cli.enterprise.main import EnterpriseConfigureCommand
 from crewai.cli.settings.main import SettingsCommand
@@ -25,7 +26,7 @@ class TestEnterpriseConfigureCommand(unittest.TestCase):
    def tearDown(self):
        shutil.rmtree(self.test_dir)

-    @patch('crewai.cli.enterprise.main.requests.get')
+    @patch('crewai.cli.enterprise.main.httpx.get')
    @patch('crewai.cli.enterprise.main.get_crewai_version')
    def test_successful_configuration(self, mock_get_version, mock_requests_get):
        mock_get_version.return_value = "1.0.0"
@@ -73,19 +74,23 @@ class TestEnterpriseConfigureCommand(unittest.TestCase):
            self.assertEqual(call_args[0], key)
            self.assertEqual(call_args[1], value)

-    @patch('crewai.cli.enterprise.main.requests.get')
+    @patch('crewai.cli.enterprise.main.httpx.get')
    @patch('crewai.cli.enterprise.main.get_crewai_version')
    def test_http_error_handling(self, mock_get_version, mock_requests_get):
        mock_get_version.return_value = "1.0.0"

        mock_response = Mock()
-        mock_response.raise_for_status.side_effect = requests.HTTPError("404 Not Found")
+        mock_response.raise_for_status.side_effect = httpx.HTTPStatusError(
+            "404 Not Found",
+            request=httpx.Request("GET", "http://test"),
+            response=httpx.Response(404),
+        )
        mock_requests_get.return_value = mock_response

        with self.assertRaises(SystemExit):
            self.enterprise_command.configure("https://enterprise.example.com")

-    @patch('crewai.cli.enterprise.main.requests.get')
+    @patch('crewai.cli.enterprise.main.httpx.get')
    @patch('crewai.cli.enterprise.main.get_crewai_version')
    def test_invalid_json_response(self, mock_get_version, mock_requests_get):
        mock_get_version.return_value = "1.0.0"
@@ -93,13 +98,13 @@ class TestEnterpriseConfigureCommand(unittest.TestCase):
        mock_response = Mock()
        mock_response.status_code = 200
        mock_response.raise_for_status.return_value = None
-        mock_response.json.side_effect = JSONDecodeError("Invalid JSON", "", 0)
+        mock_response.json.side_effect = json.JSONDecodeError("Invalid JSON", "", 0)
        mock_requests_get.return_value = mock_response

        with self.assertRaises(SystemExit):
            self.enterprise_command.configure("https://enterprise.example.com")

-    @patch('crewai.cli.enterprise.main.requests.get')
+    @patch('crewai.cli.enterprise.main.httpx.get')
    @patch('crewai.cli.enterprise.main.get_crewai_version')
    def test_missing_required_fields(self, mock_get_version, mock_requests_get):
        mock_get_version.return_value = "1.0.0"
@@ -115,7 +120,7 @@ class TestEnterpriseConfigureCommand(unittest.TestCase):
        with self.assertRaises(SystemExit):
            self.enterprise_command.configure("https://enterprise.example.com")

-    @patch('crewai.cli.enterprise.main.requests.get')
+    @patch('crewai.cli.enterprise.main.httpx.get')
    @patch('crewai.cli.enterprise.main.get_crewai_version')
    def test_settings_update_error(self, mock_get_version, mock_requests_get):
        mock_get_version.return_value = "1.0.0"
--- a/lib/crewai/tests/cli/organization/test_main.py
+++ b/lib/crewai/tests/cli/organization/test_main.py
@@ -3,7 +3,7 @@ from unittest.mock import MagicMock, patch, call

 import pytest
 from click.testing import CliRunner
-import requests
+import httpx

 from crewai.cli.organization.main import OrganizationCommand
 from crewai.cli.cli import org_list, switch, current
@@ -115,7 +115,7 @@ class TestOrganizationCommand(unittest.TestCase):
    def test_list_organizations_api_error(self, mock_console):
        self.org_command.plus_api_client = MagicMock()
        self.org_command.plus_api_client.get_organizations.side_effect = (
-            requests.exceptions.RequestException("API Error")
+            httpx.HTTPError("API Error")
        )

        with pytest.raises(SystemExit):
@@ -201,8 +201,10 @@ class TestOrganizationCommand(unittest.TestCase):
    @patch("crewai.cli.organization.main.console")
    def test_list_organizations_unauthorized(self, mock_console):
        mock_response = MagicMock()
-        mock_http_error = requests.exceptions.HTTPError(
-            "401 Client Error: Unauthorized", response=MagicMock(status_code=401)
+        mock_http_error = httpx.HTTPStatusError(
+            "401 Client Error: Unauthorized",
+            request=httpx.Request("GET", "http://test"),
+            response=httpx.Response(401),
        )

        mock_response.raise_for_status.side_effect = mock_http_error
@@ -219,8 +221,10 @@ class TestOrganizationCommand(unittest.TestCase):
    @patch("crewai.cli.organization.main.console")
    def test_switch_organization_unauthorized(self, mock_console):
        mock_response = MagicMock()
-        mock_http_error = requests.exceptions.HTTPError(
-            "401 Client Error: Unauthorized", response=MagicMock(status_code=401)
+        mock_http_error = httpx.HTTPStatusError(
+            "401 Client Error: Unauthorized",
+            request=httpx.Request("GET", "http://test"),
+            response=httpx.Response(401),
        )

        mock_response.raise_for_status.side_effect = mock_http_error
--- a/lib/crewai/tests/cli/test_plus_api.py
+++ b/lib/crewai/tests/cli/test_plus_api.py
@@ -33,9 +33,9 @@ class TestPlusAPI(unittest.TestCase):
        self.assertEqual(response, mock_response)

    def assert_request_with_org_id(
-        self, mock_make_request, method: str, endpoint: str, **kwargs
+        self, mock_client_instance, method: str, endpoint: str, **kwargs
    ):
-        mock_make_request.assert_called_once_with(
+        mock_client_instance.request.assert_called_once_with(
            method,
            f"{os.getenv('CREWAI_PLUS_URL')}{endpoint}",
            headers={
@@ -49,24 +49,25 @@ class TestPlusAPI(unittest.TestCase):
        )

    @patch("crewai.cli.plus_api.Settings")
-    @patch("requests.Session.request")
+    @patch("crewai.cli.plus_api.httpx.Client")
    def test_login_to_tool_repository_with_org_uuid(
-        self, mock_make_request, mock_settings_class
+        self, mock_client_class, mock_settings_class
    ):
        mock_settings = MagicMock()
        mock_settings.org_uuid = self.org_uuid
        mock_settings.enterprise_base_url = os.getenv('CREWAI_PLUS_URL')
        mock_settings_class.return_value = mock_settings
-        # re-initialize Client
        self.api = PlusAPI(self.api_key)

+        mock_client_instance = MagicMock()
        mock_response = MagicMock()
-        mock_make_request.return_value = mock_response
+        mock_client_instance.request.return_value = mock_response
+        mock_client_class.return_value.__enter__.return_value = mock_client_instance

        response = self.api.login_to_tool_repository()

        self.assert_request_with_org_id(
-            mock_make_request, "POST", "/crewai_plus/api/v1/tools/login"
+            mock_client_instance, "POST", "/crewai_plus/api/v1/tools/login"
        )
        self.assertEqual(response, mock_response)

@@ -82,23 +83,23 @@ class TestPlusAPI(unittest.TestCase):
        self.assertEqual(response, mock_response)

    @patch("crewai.cli.plus_api.Settings")
-    @patch("requests.Session.request")
-    def test_get_tool_with_org_uuid(self, mock_make_request, mock_settings_class):
+    @patch("crewai.cli.plus_api.httpx.Client")
+    def test_get_tool_with_org_uuid(self, mock_client_class, mock_settings_class):
        mock_settings = MagicMock()
        mock_settings.org_uuid = self.org_uuid
        mock_settings.enterprise_base_url = os.getenv('CREWAI_PLUS_URL')
        mock_settings_class.return_value = mock_settings
-        # re-initialize Client
        self.api = PlusAPI(self.api_key)

-        # Set up mock response
+        mock_client_instance = MagicMock()
        mock_response = MagicMock()
-        mock_make_request.return_value = mock_response
+        mock_client_instance.request.return_value = mock_response
+        mock_client_class.return_value.__enter__.return_value = mock_client_instance

        response = self.api.get_tool("test_tool_handle")

        self.assert_request_with_org_id(
-            mock_make_request, "GET", "/crewai_plus/api/v1/tools/test_tool_handle"
+            mock_client_instance, "GET", "/crewai_plus/api/v1/tools/test_tool_handle"
        )
        self.assertEqual(response, mock_response)

@@ -130,18 +131,18 @@ class TestPlusAPI(unittest.TestCase):
        self.assertEqual(response, mock_response)

    @patch("crewai.cli.plus_api.Settings")
-    @patch("requests.Session.request")
-    def test_publish_tool_with_org_uuid(self, mock_make_request, mock_settings_class):
+    @patch("crewai.cli.plus_api.httpx.Client")
+    def test_publish_tool_with_org_uuid(self, mock_client_class, mock_settings_class):
        mock_settings = MagicMock()
        mock_settings.org_uuid = self.org_uuid
        mock_settings.enterprise_base_url = os.getenv('CREWAI_PLUS_URL')
        mock_settings_class.return_value = mock_settings
-        # re-initialize Client
        self.api = PlusAPI(self.api_key)

-        # Set up mock response
+        mock_client_instance = MagicMock()
        mock_response = MagicMock()
-        mock_make_request.return_value = mock_response
+        mock_client_instance.request.return_value = mock_response
+        mock_client_class.return_value.__enter__.return_value = mock_client_instance

        handle = "test_tool_handle"
        public = True
@@ -153,7 +154,6 @@ class TestPlusAPI(unittest.TestCase):
            handle, public, version, description, encoded_file
        )

-        # Expected params including organization_uuid
        expected_params = {
            "handle": handle,
            "public": public,
@@ -164,7 +164,7 @@ class TestPlusAPI(unittest.TestCase):
        }

        self.assert_request_with_org_id(
-            mock_make_request, "POST", "/crewai_plus/api/v1/tools", json=expected_params
+            mock_client_instance, "POST", "/crewai_plus/api/v1/tools", json=expected_params
        )
        self.assertEqual(response, mock_response)

@@ -195,20 +195,19 @@ class TestPlusAPI(unittest.TestCase):
        )
        self.assertEqual(response, mock_response)

-    @patch("crewai.cli.plus_api.requests.Session")
-    def test_make_request(self, mock_session):
+    @patch("crewai.cli.plus_api.httpx.Client")
+    def test_make_request(self, mock_client_class):
+        mock_client_instance = MagicMock()
        mock_response = MagicMock()
-
-        mock_session_instance = mock_session.return_value
-        mock_session_instance.request.return_value = mock_response
+        mock_client_instance.request.return_value = mock_response
+        mock_client_class.return_value.__enter__.return_value = mock_client_instance

        response = self.api._make_request("GET", "test_endpoint")

-        mock_session.assert_called_once()
-        mock_session_instance.request.assert_called_once_with(
+        mock_client_class.assert_called_once_with(trust_env=False, verify=True)
+        mock_client_instance.request.assert_called_once_with(
            "GET", f"{self.api.base_url}/test_endpoint", headers=self.api.headers
        )
-        mock_session_instance.trust_env = False
        self.assertEqual(response, mock_response)

    @patch("crewai.cli.plus_api.PlusAPI._make_request")
--- a/lib/crewai/tests/cli/tools/test_main.py
+++ b/lib/crewai/tests/cli/tools/test_main.py
@@ -351,7 +351,7 @@ def test_publish_api_error(
    mock_response = MagicMock()
    mock_response.status_code = 500
    mock_response.json.return_value = {"error": "Internal Server Error"}
-    mock_response.ok = False
+    mock_response.is_success = False
    mock_publish.return_value = mock_response

    with raises(SystemExit):
--- a/lib/crewai/tests/cli/triggers/test_main.py
+++ b/lib/crewai/tests/cli/triggers/test_main.py
@@ -3,7 +3,7 @@ import subprocess
 import unittest
 from unittest.mock import Mock, patch

-import requests
+import httpx
 from crewai.cli.triggers.main import TriggersCommand


@@ -21,7 +21,7 @@ class TestTriggersCommand(unittest.TestCase):

    @patch("crewai.cli.triggers.main.console.print")
    def test_list_triggers_success(self, mock_console_print):
-        mock_response = Mock(spec=requests.Response)
+        mock_response = Mock(spec=httpx.Response)
        mock_response.status_code = 200
        mock_response.ok = True
        mock_response.json.return_value = {
@@ -50,7 +50,7 @@ class TestTriggersCommand(unittest.TestCase):

    @patch("crewai.cli.triggers.main.console.print")
    def test_list_triggers_no_apps(self, mock_console_print):
-        mock_response = Mock(spec=requests.Response)
+        mock_response = Mock(spec=httpx.Response)
        mock_response.status_code = 200
        mock_response.ok = True
        mock_response.json.return_value = {"apps": []}
@@ -81,7 +81,7 @@ class TestTriggersCommand(unittest.TestCase):
    @patch("crewai.cli.triggers.main.console.print")
    @patch.object(TriggersCommand, "_run_crew_with_payload")
    def test_execute_with_trigger_success(self, mock_run_crew, mock_console_print):
-        mock_response = Mock(spec=requests.Response)
+        mock_response = Mock(spec=httpx.Response)
        mock_response.status_code = 200
        mock_response.ok = True
        mock_response.json.return_value = {
@@ -99,7 +99,7 @@ class TestTriggersCommand(unittest.TestCase):

    @patch("crewai.cli.triggers.main.console.print")
    def test_execute_with_trigger_not_found(self, mock_console_print):
-        mock_response = Mock(spec=requests.Response)
+        mock_response = Mock(spec=httpx.Response)
        mock_response.status_code = 404
        mock_response.json.return_value = {"error": "Trigger not found"}
        self.mock_client.get_trigger_payload.return_value = mock_response
@@ -159,7 +159,7 @@ class TestTriggersCommand(unittest.TestCase):

    @patch("crewai.cli.triggers.main.console.print")
    def test_execute_with_trigger_with_default_error_message(self, mock_console_print):
-        mock_response = Mock(spec=requests.Response)
+        mock_response = Mock(spec=httpx.Response)
        mock_response.status_code = 404
        mock_response.json.return_value = {}
        self.mock_client.get_trigger_payload.return_value = mock_response
--- a/lib/crewai/tests/mcp/test_mcp_delegation.py
+++ b/lib/crewai/tests/mcp/test_mcp_delegation.py
@@ -0,0 +1,225 @@
+"""Tests for MCP tools loading during delegation (Issue #4571).
+
+When an agent with MCP servers configured is used as a sub-agent via delegation,
+its MCP tools must be loaded even though the Crew's _prepare_tools() is not called
+for the delegated-to agent.
+"""
+
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from crewai.agent.core import Agent
+from crewai.agent.utils import _inject_mcp_tools, prepare_tools
+from crewai.mcp.config import MCPServerHTTP
+from crewai.task import Task
+from crewai.tools.base_tool import BaseTool
+
+
+def _make_mock_tool(name: str) -> MagicMock:
+    """Create a MagicMock that looks like a BaseTool with the given name."""
+    tool = MagicMock(spec=BaseTool)
+    tool.name = name
+    return tool
+
+
+@pytest.fixture
+def http_config():
+    """Create a sample MCPServerHTTP configuration."""
+    return MCPServerHTTP(url="https://api.example.com/mcp")
+
+
+@pytest.fixture
+def sub_agent_with_mcp(http_config):
+    """Create an agent with MCP servers configured (the delegated-to agent)."""
+    return Agent(
+        role="MCP Sub Agent",
+        goal="Execute tasks using MCP tools",
+        backstory="An agent that uses MCP server tools",
+        mcps=[http_config],
+        allow_delegation=False,
+    )
+
+
+@pytest.fixture
+def sub_agent_without_mcp():
+    """Create an agent without MCP servers."""
+    return Agent(
+        role="Regular Sub Agent",
+        goal="Execute tasks normally",
+        backstory="An agent without MCP tools",
+        allow_delegation=False,
+    )
+
+
+class TestInjectMcpTools:
+    """Tests for the _inject_mcp_tools helper function."""
+
+    def test_injects_mcp_tools_when_agent_has_mcps(self, sub_agent_with_mcp):
+        """MCP tools should be injected when agent has mcps configured."""
+        mock_mcp_tools = [_make_mock_tool("mcp_search"), _make_mock_tool("mcp_fetch")]
+
+        with patch.object(Agent, "get_mcp_tools", return_value=mock_mcp_tools):
+            tools: list[BaseTool] = []
+            result = _inject_mcp_tools(sub_agent_with_mcp, tools)
+
+            assert len(result) == 2
+            tool_names = {t.name for t in result}
+            assert "mcp_search" in tool_names
+            assert "mcp_fetch" in tool_names
+
+    def test_does_not_inject_when_agent_has_no_mcps(self, sub_agent_without_mcp):
+        """No MCP tools should be injected when agent has no mcps."""
+        tools: list[BaseTool] = []
+        result = _inject_mcp_tools(sub_agent_without_mcp, tools)
+        assert len(result) == 0
+
+    def test_does_not_duplicate_existing_mcp_tools(self, sub_agent_with_mcp):
+        """MCP tools already in the list should not be duplicated."""
+        existing_search = _make_mock_tool("mcp_search")
+        mock_mcp_tools = [_make_mock_tool("mcp_search"), _make_mock_tool("mcp_fetch")]
+
+        with patch.object(Agent, "get_mcp_tools", return_value=mock_mcp_tools):
+            tools = [existing_search]
+            result = _inject_mcp_tools(sub_agent_with_mcp, tools)
+
+            # Should have 2 tools: existing mcp_search + new mcp_fetch
+            assert len(result) == 2
+            tool_names = [t.name for t in result]
+            assert tool_names.count("mcp_search") == 1
+            assert tool_names.count("mcp_fetch") == 1
+
+    def test_preserves_existing_tools(self, sub_agent_with_mcp):
+        """Existing non-MCP tools should be preserved after injection."""
+        mock_mcp_tools = [_make_mock_tool("mcp_search"), _make_mock_tool("mcp_fetch")]
+
+        with patch.object(Agent, "get_mcp_tools", return_value=mock_mcp_tools):
+            existing_tool = _make_mock_tool("existing_tool")
+            tools = [existing_tool]
+
+            result = _inject_mcp_tools(sub_agent_with_mcp, tools)
+
+            assert len(result) == 3  # 1 existing + 2 MCP
+            tool_names = {t.name for t in result}
+            assert "existing_tool" in tool_names
+            assert "mcp_search" in tool_names
+            assert "mcp_fetch" in tool_names
+
+    def test_handles_mcp_loading_failure_gracefully(self, sub_agent_with_mcp):
+        """If MCP tool loading fails, existing tools should be returned unmodified."""
+        with patch.object(
+            Agent, "get_mcp_tools", side_effect=Exception("Connection failed")
+        ):
+            existing_tool = _make_mock_tool("my_tool")
+            tools = [existing_tool]
+
+            result = _inject_mcp_tools(sub_agent_with_mcp, tools)
+
+            assert len(result) == 1
+            assert result[0].name == "my_tool"
+
+    def test_handles_empty_mcp_tools_list(self, sub_agent_with_mcp):
+        """If MCP server returns empty tools list, original tools are unchanged."""
+        with patch.object(Agent, "get_mcp_tools", return_value=[]):
+            existing_tool = _make_mock_tool("my_tool")
+            tools = [existing_tool]
+
+            result = _inject_mcp_tools(sub_agent_with_mcp, tools)
+
+            assert len(result) == 1
+            assert result[0].name == "my_tool"
+
+    def test_handles_agent_with_empty_mcps_list(self):
+        """An agent with an empty mcps list should not trigger MCP loading."""
+        agent = Agent(
+            role="Agent",
+            goal="Test",
+            backstory="Test",
+            mcps=[],
+            allow_delegation=False,
+        )
+        tools: list[BaseTool] = []
+        result = _inject_mcp_tools(agent, tools)
+        assert len(result) == 0
+
+
+class TestPrepareToolsWithMcp:
+    """Tests for prepare_tools function with MCP integration."""
+
+    def test_prepare_tools_injects_mcp_when_tools_is_none(
+        self, sub_agent_with_mcp
+    ):
+        """When tools=None (delegation scenario), MCP tools should be loaded."""
+        task = Task(
+            description="Test task for delegation",
+            agent=sub_agent_with_mcp,
+            expected_output="Test output",
+        )
+
+        mock_mcp_tools = [_make_mock_tool("mcp_search"), _make_mock_tool("mcp_fetch")]
+        with patch.object(Agent, "get_mcp_tools", return_value=mock_mcp_tools), \
+             patch.object(Agent, "create_agent_executor"):
+            result = prepare_tools(sub_agent_with_mcp, None, task)
+
+            tool_names = {t.name for t in result}
+            assert "mcp_search" in tool_names
+            assert "mcp_fetch" in tool_names
+
+    def test_prepare_tools_no_mcp_when_agent_has_no_mcps(
+        self, sub_agent_without_mcp
+    ):
+        """When agent has no mcps, prepare_tools should behave normally."""
+        task = Task(
+            description="Test task",
+            agent=sub_agent_without_mcp,
+            expected_output="Test output",
+        )
+
+        with patch.object(Agent, "create_agent_executor"):
+            result = prepare_tools(sub_agent_without_mcp, None, task)
+            assert len(result) == 0
+
+    def test_prepare_tools_merges_explicit_tools_and_mcp(
+        self, sub_agent_with_mcp
+    ):
+        """When explicit tools are passed + agent has mcps, both should be present."""
+        task = Task(
+            description="Test task",
+            agent=sub_agent_with_mcp,
+            expected_output="Test output",
+        )
+
+        explicit_tool = _make_mock_tool("custom_tool")
+        mock_mcp_tools = [_make_mock_tool("mcp_search")]
+        with patch.object(Agent, "get_mcp_tools", return_value=mock_mcp_tools), \
+             patch.object(Agent, "create_agent_executor"):
+            result = prepare_tools(sub_agent_with_mcp, [explicit_tool], task)
+
+            tool_names = {t.name for t in result}
+            assert "custom_tool" in tool_names
+            assert "mcp_search" in tool_names
+
+
+class TestDelegationWithMcp:
+    """Tests for the full delegation flow with MCP-configured sub-agents."""
+
+    def test_delegation_tool_loads_mcp_tools_for_sub_agent(
+        self, sub_agent_with_mcp
+    ):
+        """When DelegateWorkTool delegates to an agent with MCPs,
+        the MCP tools should be loaded during execute_task."""
+        task = Task(
+            description="Search for AI news",
+            agent=sub_agent_with_mcp,
+            expected_output="AI news results",
+        )
+
+        mock_mcp_tools = [_make_mock_tool("mcp_search")]
+
+        with patch.object(Agent, "get_mcp_tools", return_value=mock_mcp_tools), \
+             patch.object(Agent, "create_agent_executor"), \
+             patch.object(Agent, "_execute_without_timeout", return_value="Found AI news"):
+            # Simulate what DelegateWorkTool does: call execute_task with no tools
+            result = sub_agent_with_mcp.execute_task(task, "context")
+
+            assert result == "Found AI news"
--- a/uv.lock
+++ b/uv.lock
@@ -1096,6 +1096,7 @@ dependencies = [
    { name = "appdirs" },
    { name = "chromadb" },
    { name = "click" },
+    { name = "httpx" },
    { name = "instructor" },
    { name = "json-repair" },
    { name = "json5" },
@@ -1195,6 +1196,7 @@ requires-dist = [
    { name = "crewai-tools", marker = "extra == 'tools'", editable = "lib/crewai-tools" },
    { name = "docling", marker = "extra == 'docling'", specifier = "~=2.63.0" },
    { name = "google-genai", marker = "extra == 'google-genai'", specifier = "~=1.49.0" },
+    { name = "httpx", specifier = "~=0.28.1" },
    { name = "httpx-auth", marker = "extra == 'a2a'", specifier = "~=0.23.1" },
    { name = "httpx-sse", marker = "extra == 'a2a'", specifier = "~=0.4.0" },
    { name = "ibm-watsonx-ai", marker = "extra == 'watson'", specifier = "~=1.3.39" },
Author	SHA1	Message	Date
Devin AI	50d2e4c1b0	fix: inject MCP tools during delegation (fixes #4571 ) When an agent with MCP servers configured is used as a sub-agent via delegation, its MCP tools were not loaded because the Crew's _prepare_tools() is not called for the delegated-to agent. This fix adds _inject_mcp_tools() to agent/utils.py and calls it from prepare_tools(), which is invoked by both execute_task() and aexecute_task(). MCP tools are now loaded on-demand when the agent has mcps configured, with deduplication and graceful error handling. Also adds 11 tests covering: - MCP tool injection with/without mcps - Deduplication of existing tools - Graceful failure handling - prepare_tools integration - Full delegation flow Co-Authored-By: João <joao@crewai.com>	2026-02-23 15:49:58 +00:00
Greyson LaLonde	51754899a2	feat: migrate CLI http client from requests to httpx Some checks failed Build uv cache / build-cache (3.10) (push) Has been cancelled Details Build uv cache / build-cache (3.11) (push) Has been cancelled Details Build uv cache / build-cache (3.12) (push) Has been cancelled Details Build uv cache / build-cache (3.13) (push) Has been cancelled Details CodeQL Advanced / Analyze (actions) (push) Has been cancelled Details CodeQL Advanced / Analyze (python) (push) Has been cancelled Details Mark stale issues and pull requests / stale (push) Has been cancelled Details	2026-02-20 18:21:05 -05:00
Greyson LaLonde	71b4f8402a	fix: ensure callbacks are ran/awaited if promise Some checks failed CodeQL Advanced / Analyze (actions) (push) Has been cancelled Details CodeQL Advanced / Analyze (python) (push) Has been cancelled Details Build uv cache / build-cache (3.12) (push) Has been cancelled Details Build uv cache / build-cache (3.13) (push) Has been cancelled Details Build uv cache / build-cache (3.10) (push) Has been cancelled Details Build uv cache / build-cache (3.11) (push) Has been cancelled Details	2026-02-20 13:15:50 -05:00