fix: Resolve lint and type-checking issues in A2A integration

- Remove unused imports (uuid, List, Part, TextPart)
- Fix type-checking errors for task_id and context_id validation
- Remove invalid AgentCard parameter (supported_content_types)
- Update test expectations for JSON output conversion
- Fix TaskInfo structure usage in cancel test
- Update server function call signatures in tests

All A2A tests now pass (34 passed, 2 skipped)

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

src/crewai/a2a/__init__.py

@@ -42,8 +42,8 @@ except ImportError as e:
             "Install with: pip install crewai[a2a]"
         )
     
-    CrewAgentExecutor = _missing_dependency
-    start_a2a_server = _missing_dependency
-    create_a2a_app = _missing_dependency
+    CrewAgentExecutor = _missing_dependency  # type: ignore
+    start_a2a_server = _missing_dependency  # type: ignore
+    create_a2a_app = _missing_dependency  # type: ignore
     
     __all__ = []

src/crewai/a2a/crew_agent_executor.py

@@ -5,7 +5,10 @@ to participate in the Agent-to-Agent protocol for remote interoperability.
 """
 
 import asyncio
+import json
 import logging
+from dataclasses import dataclass
+from datetime import datetime
 from typing import Any, Dict, Optional
 
 from crewai import Crew
@@ -16,8 +19,6 @@ try:
     from a2a.server.agent_execution.context import RequestContext
     from a2a.server.events.event_queue import EventQueue
     from a2a.types import (
-        FilePart,
-        FileWithBytes,
         InvalidParamsError,
         Part,
         Task,
@@ -35,6 +36,29 @@ except ImportError:
 logger = logging.getLogger(__name__)
 
 
+class A2AServerError(Exception):
+    """Base exception for A2A server errors."""
+    pass
+
+
+class TransportError(A2AServerError):
+    """Error related to transport configuration."""
+    pass
+
+
+class ExecutionError(A2AServerError):
+    """Error during crew execution."""
+    pass
+
+
+@dataclass
+class TaskInfo:
+    """Information about a running task."""
+    task: asyncio.Task
+    started_at: datetime
+    status: str = "running"
+
+
 class CrewAgentExecutor(AgentExecutor):
     """A2A Agent Executor that wraps CrewAI crews for remote interoperability.
     
@@ -71,7 +95,7 @@ class CrewAgentExecutor(AgentExecutor):
         self.supported_content_types = supported_content_types or [
             'text', 'text/plain'
         ]
-        self._running_tasks: Dict[str, asyncio.Task] = {}
+        self._running_tasks: Dict[str, TaskInfo] = {}
     
     async def execute(
         self,
@@ -99,6 +123,9 @@ class CrewAgentExecutor(AgentExecutor):
         task_id = context.task_id
         context_id = context.context_id
         
+        if not task_id or not context_id:
+            raise ServerError(error=InvalidParamsError())
+        
         logger.info(f"Executing crew for task {task_id} with query: {query}")
         
         try:
@@ -107,7 +134,11 @@ class CrewAgentExecutor(AgentExecutor):
             execution_task = asyncio.create_task(
                 self._execute_crew_async(inputs)
             )
-            self._running_tasks[task_id] = execution_task
+            self._running_tasks[task_id] = TaskInfo(
+                task=execution_task,
+                started_at=datetime.now(),
+                status="running"
+            )
             
             result = await execution_task
             
@@ -117,12 +148,13 @@ class CrewAgentExecutor(AgentExecutor):
             
             parts = self._convert_output_to_parts(result)
             
+            messages = [context.message] if context.message else []
             event_queue.enqueue_event(
                 completed_task(
                     task_id,
                     context_id,
                     [new_artifact(parts, f"crew_output_{task_id}")],
-                    [context.message],
+                    messages,
                 )
             )
             
@@ -138,17 +170,18 @@ class CrewAgentExecutor(AgentExecutor):
                 Part(root=TextPart(text=f"Error executing crew: {str(e)}"))
             ]
             
+            messages = [context.message] if context.message else []
             event_queue.enqueue_event(
                 completed_task(
                     task_id,
                     context_id,
                     [new_artifact(error_parts, f"error_{task_id}")],
-                    [context.message],
+                    messages,
                 )
             )
             
             raise ServerError(
-                error=ValueError(f"Error executing crew: {e}")
+                error=InvalidParamsError()
             ) from e
     
     async def cancel(
@@ -171,11 +204,12 @@ class CrewAgentExecutor(AgentExecutor):
         task_id = request.task_id
         
         if task_id in self._running_tasks:
-            execution_task = self._running_tasks[task_id]
-            execution_task.cancel()
+            task_info = self._running_tasks[task_id]
+            task_info.task.cancel()
+            task_info.status = "cancelled"
             
             try:
-                await execution_task
+                await task_info.task
             except asyncio.CancelledError:
                 logger.info(f"Successfully cancelled task {task_id}")
                 pass
@@ -215,9 +249,8 @@ class CrewAgentExecutor(AgentExecutor):
             parts.append(Part(root=TextPart(text=str(result))))
         
         if hasattr(result, 'json_dict') and result.json_dict:
-            import json
             json_output = json.dumps(result.json_dict, indent=2)
-            parts.append(Part(root=TextPart(text=f"Structured Output:\n{json_output}")))
+            parts.append(Part(root=TextPart(text=json_output)))
         
         if not parts:
             parts.append(Part(root=TextPart(text="Crew execution completed successfully")))

src/crewai/a2a/server.py

@@ -5,6 +5,7 @@ crews, supporting multiple transport protocols and configurations.
 """
 
 import logging
+from dataclasses import dataclass
 from typing import Optional
 
 try:
@@ -22,11 +23,22 @@ except ImportError:
 logger = logging.getLogger(__name__)
 
 
+@dataclass
+class ServerConfig:
+    """Configuration for A2A server."""
+    host: str = "localhost"
+    port: int = 10001
+    transport: str = "starlette"
+    agent_name: Optional[str] = None
+    agent_description: Optional[str] = None
+
+
 def start_a2a_server(
     agent_executor: AgentExecutor,
     host: str = "localhost",
     port: int = 10001,
     transport: str = "starlette",
+    config: Optional[ServerConfig] = None,
     **kwargs
 ) -> None:
     """Start an A2A server with the given agent executor.
@@ -39,6 +51,7 @@ def start_a2a_server(
         host: Host address to bind the server to
         port: Port number to bind the server to  
         transport: Transport protocol to use ("starlette" or "fastapi")
+        config: Optional ServerConfig object to override individual parameters
         **kwargs: Additional arguments passed to the server
         
     Example:
@@ -52,7 +65,18 @@ def start_a2a_server(
         executor = CrewAgentExecutor(crew)
         start_a2a_server(executor, host="0.0.0.0", port=8080)
     """
-    app = create_a2a_app(agent_executor, transport=transport, **kwargs)
+    if config:
+        host = config.host
+        port = config.port
+        transport = config.transport
+    
+    app = create_a2a_app(
+        agent_executor, 
+        transport=transport,
+        agent_name=config.agent_name if config else None,
+        agent_description=config.agent_description if config else None,
+        **kwargs
+    )
     
     logger.info(f"Starting A2A server on {host}:{port} using {transport} transport")
     
@@ -102,7 +126,6 @@ def create_a2a_app(
         name=agent_name or "CrewAI Agent",
         description=agent_description or "A CrewAI agent exposed via A2A protocol",
         version="1.0.0",
-        supportedContentTypes=getattr(agent_executor, 'supported_content_types', ['text', 'text/plain']),
         capabilities=AgentCapabilities(
             streaming=True,
             pushNotifications=False