Add explicit type annotations for agents_config and tasks_config

Fixes #3801

This commit addresses the issue where agents_config and tasks_config
in CrewBase-decorated classes lacked explicit type annotations, making
the code un-Pythonic and reducing IDE/type checker support.

Changes:
- Added AgentsConfigDict and TasksConfigDict type aliases
- Updated load_configurations to use cast() for proper typing
- Updated CrewInstance Protocol to use typed config dictionaries
- Exported type aliases from crewai.project for user convenience
- Updated TypedDicts to support both raw YAML and processed values
- Added comprehensive tests for config loading and type annotations

The type aliases allow users to import and use proper types:
  from crewai.project import AgentConfig, AgentsConfigDict

This provides better IDE autocomplete and static type checking when
accessing self.agents_config and self.tasks_config in CrewBase classes.

Co-Authored-By: João <joao@crewai.com>

lib/crewai/src/crewai/project/__init__.py

@@ -13,11 +13,21 @@ from crewai.project.annotations import (
     task,
     tool,
 )
-from crewai.project.crew_base import CrewBase
+from crewai.project.crew_base import (
+    AgentConfig,
+    AgentsConfigDict,
+    CrewBase,
+    TaskConfig,
+    TasksConfigDict,
+)
 
 
 __all__ = [
+    "AgentConfig",
+    "AgentsConfigDict",
     "CrewBase",
+    "TaskConfig",
+    "TasksConfigDict",
     "after_kickoff",
     "agent",
     "before_kickoff",

lib/crewai/src/crewai/project/crew_base.py

@@ -52,11 +52,11 @@ class AgentConfig(TypedDict, total=False):
     allow_delegation: bool
     max_iter: int
     max_tokens: int
-    callbacks: list[str]
+    callbacks: list[str] | list[Any]
 
-    # LLM configuration
-    llm: str
-    function_calling_llm: str
+    # LLM configuration (can be string references or resolved instances)
+    llm: str | Any
+    function_calling_llm: str | Any
     use_system_prompt: bool
 
     # Template configuration
@@ -66,7 +66,7 @@ class AgentConfig(TypedDict, total=False):
 
     # Tools and handlers (can be string references or instances)
     tools: list[str] | list[BaseTool]
-    step_callback: str
+    step_callback: str | Any
     cache_handler: str | CacheHandler
 
     # Code execution
@@ -111,18 +111,18 @@ class TaskConfig(TypedDict, total=False):
     description: str
     expected_output: str
 
-    # Agent and context
-    agent: str
-    context: list[str]
+    # Agent and context (can be string references or resolved instances)
+    agent: str | Any
+    context: list[str] | list[Any]
 
     # Tools and callbacks (can be string references or instances)
     tools: list[str] | list[BaseTool]
-    callback: str
-    callbacks: list[str]
+    callback: str | Any
+    callbacks: list[str] | list[Any]
 
-    # Output configuration
-    output_json: str
-    output_pydantic: str
+    # Output configuration (can be string references or resolved class wrappers)
+    output_json: str | Any
+    output_pydantic: str | Any
     output_file: str
     create_directory: bool
 
@@ -139,6 +139,10 @@ class TaskConfig(TypedDict, total=False):
     allow_crewai_trigger_context: bool
 
 
+AgentsConfigDict = dict[str, AgentConfig]
+TasksConfigDict = dict[str, TaskConfig]
+
+
 load_dotenv()
 
 CallableT = TypeVar("CallableT", bound=Callable[..., Any])
@@ -378,8 +382,14 @@ def load_configurations(self: CrewInstance) -> None:
     Args:
         self: Crew instance with configuration paths.
     """
-    self.agents_config = self._load_config(self.original_agents_config_path, "agent")
-    self.tasks_config = self._load_config(self.original_tasks_config_path, "task")
+    self.agents_config = cast(
+        AgentsConfigDict,
+        self._load_config(self.original_agents_config_path, "agent"),
+    )
+    self.tasks_config = cast(
+        TasksConfigDict,
+        self._load_config(self.original_tasks_config_path, "task"),
+    )
 
 
 def load_yaml(config_path: Path) -> dict[str, Any]:

lib/crewai/src/crewai/project/wrappers.py

@@ -22,6 +22,12 @@ from typing_extensions import Self
 if TYPE_CHECKING:
     from crewai import Agent, Crew, Task
     from crewai.crews.crew_output import CrewOutput
+    from crewai.project.crew_base import (
+        AgentConfig,
+        AgentsConfigDict,
+        TaskConfig,
+        TasksConfigDict,
+    )
     from crewai.tools import BaseTool
 
 
@@ -75,8 +81,8 @@ class CrewInstance(Protocol):
     base_directory: Path
     original_agents_config_path: str
     original_tasks_config_path: str
-    agents_config: dict[str, Any]
-    tasks_config: dict[str, Any]
+    agents_config: AgentsConfigDict
+    tasks_config: TasksConfigDict
     mcp_server_params: Any
     mcp_connect_timeout: int
 
@@ -90,7 +96,7 @@ class CrewInstance(Protocol):
     def _map_agent_variables(
         self,
         agent_name: str,
-        agent_info: dict[str, Any],
+        agent_info: AgentConfig,
         llms: dict[str, Callable[..., Any]],
         tool_functions: dict[str, Callable[..., Any]],
         cache_handler_functions: dict[str, Callable[..., Any]],
@@ -99,7 +105,7 @@ class CrewInstance(Protocol):
     def _map_task_variables(
         self,
         task_name: str,
-        task_info: dict[str, Any],
+        task_info: TaskConfig,
         agents: dict[str, Callable[..., Any]],
         tasks: dict[str, Callable[..., Any]],
         output_json_functions: dict[str, Callable[..., Any]],

lib/crewai/tests/project/test_crew_base_configs.py

@@ -0,0 +1,193 @@
+"""Tests for CrewBase configuration type annotations."""
+
+from pathlib import Path
+
+import pytest
+
+from crewai.project import AgentConfig, AgentsConfigDict, CrewBase, TaskConfig, TasksConfigDict, agent, task
+
+
+def test_agents_config_loads_as_dict(tmp_path: Path) -> None:
+    """Test that agents_config loads as a properly typed dictionary."""
+    agents_yaml = tmp_path / "agents.yaml"
+    agents_yaml.write_text(
+        """
+researcher:
+  role: "Research Analyst"
+  goal: "Find accurate information"
+  backstory: "Expert researcher with years of experience"
+"""
+    )
+
+    tasks_yaml = tmp_path / "tasks.yaml"
+    tasks_yaml.write_text(
+        """
+research_task:
+  description: "Research the topic"
+  expected_output: "A comprehensive report"
+"""
+    )
+
+    @CrewBase
+    class TestCrew:
+        agents_config = str(agents_yaml)
+        tasks_config = str(tasks_yaml)
+
+        @agent
+        def researcher(self):
+            from crewai import Agent
+            return Agent(config=self.agents_config["researcher"])
+
+        @task
+        def research_task(self):
+            from crewai import Task
+            return Task(config=self.tasks_config["research_task"])
+
+    crew_instance = TestCrew()
+
+    assert isinstance(crew_instance.agents_config, dict)
+    assert "researcher" in crew_instance.agents_config
+    assert crew_instance.agents_config["researcher"]["role"] == "Research Analyst"
+    assert crew_instance.agents_config["researcher"]["goal"] == "Find accurate information"
+    assert crew_instance.agents_config["researcher"]["backstory"] == "Expert researcher with years of experience"
+
+
+def test_tasks_config_loads_as_dict(tmp_path: Path) -> None:
+    """Test that tasks_config loads as a properly typed dictionary."""
+    agents_yaml = tmp_path / "agents.yaml"
+    agents_yaml.write_text(
+        """
+writer:
+  role: "Content Writer"
+  goal: "Write engaging content"
+  backstory: "Experienced content writer"
+"""
+    )
+
+    tasks_yaml = tmp_path / "tasks.yaml"
+    tasks_yaml.write_text(
+        """
+writing_task:
+  description: "Write an article"
+  expected_output: "A well-written article"
+  agent: "writer"
+"""
+    )
+
+    @CrewBase
+    class TestCrew:
+        agents_config = str(agents_yaml)
+        tasks_config = str(tasks_yaml)
+
+        @agent
+        def writer(self):
+            from crewai import Agent
+            return Agent(config=self.agents_config["writer"])
+
+        @task
+        def writing_task(self):
+            from crewai import Task
+            return Task(config=self.tasks_config["writing_task"])
+
+    crew_instance = TestCrew()
+
+    assert isinstance(crew_instance.tasks_config, dict)
+    assert "writing_task" in crew_instance.tasks_config
+    assert crew_instance.tasks_config["writing_task"]["description"] == "Write an article"
+    assert crew_instance.tasks_config["writing_task"]["expected_output"] == "A well-written article"
+    
+    from crewai import Agent
+    assert isinstance(crew_instance.tasks_config["writing_task"]["agent"], Agent)
+    assert crew_instance.tasks_config["writing_task"]["agent"].role == "Content Writer"
+
+
+def test_empty_config_files_load_as_empty_dicts(tmp_path: Path) -> None:
+    """Test that empty config files load as empty dictionaries."""
+    agents_yaml = tmp_path / "agents.yaml"
+    agents_yaml.write_text("")
+
+    tasks_yaml = tmp_path / "tasks.yaml"
+    tasks_yaml.write_text("")
+
+    @CrewBase
+    class TestCrew:
+        agents_config = str(agents_yaml)
+        tasks_config = str(tasks_yaml)
+
+    crew_instance = TestCrew()
+
+    assert isinstance(crew_instance.agents_config, dict)
+    assert isinstance(crew_instance.tasks_config, dict)
+    assert len(crew_instance.agents_config) == 0
+    assert len(crew_instance.tasks_config) == 0
+
+
+def test_missing_config_files_load_as_empty_dicts(tmp_path: Path) -> None:
+    """Test that missing config files load as empty dictionaries with warning."""
+    nonexistent_agents = tmp_path / "nonexistent_agents.yaml"
+    nonexistent_tasks = tmp_path / "nonexistent_tasks.yaml"
+
+    @CrewBase
+    class TestCrew:
+        agents_config = str(nonexistent_agents)
+        tasks_config = str(nonexistent_tasks)
+
+    crew_instance = TestCrew()
+
+    assert isinstance(crew_instance.agents_config, dict)
+    assert isinstance(crew_instance.tasks_config, dict)
+    assert len(crew_instance.agents_config) == 0
+    assert len(crew_instance.tasks_config) == 0
+
+
+def test_config_types_are_exported() -> None:
+    """Test that AgentConfig, TaskConfig, and type aliases are properly exported."""
+    from crewai.project import AgentConfig, AgentsConfigDict, TaskConfig, TasksConfigDict
+
+    assert AgentConfig is not None
+    assert TaskConfig is not None
+    assert AgentsConfigDict is not None
+    assert TasksConfigDict is not None
+
+
+def test_agents_config_type_annotation_exists(tmp_path: Path) -> None:
+    """Test that agents_config has proper type annotation at runtime."""
+    agents_yaml = tmp_path / "agents.yaml"
+    agents_yaml.write_text(
+        """
+analyst:
+  role: "Data Analyst"
+  goal: "Analyze data"
+"""
+    )
+
+    tasks_yaml = tmp_path / "tasks.yaml"
+    tasks_yaml.write_text(
+        """
+analysis:
+  description: "Analyze the data"
+  expected_output: "Analysis report"
+"""
+    )
+
+    @CrewBase
+    class TestCrew:
+        agents_config = str(agents_yaml)
+        tasks_config = str(tasks_yaml)
+
+        @agent
+        def analyst(self):
+            from crewai import Agent
+            return Agent(config=self.agents_config["analyst"])
+
+        @task
+        def analysis(self):
+            from crewai import Task
+            return Task(config=self.tasks_config["analysis"])
+
+    crew_instance = TestCrew()
+
+    assert hasattr(crew_instance, "agents_config")
+    assert hasattr(crew_instance, "tasks_config")
+    assert isinstance(crew_instance.agents_config, dict)
+    assert isinstance(crew_instance.tasks_config, dict)