Implement A2A protocol support for recursive agent invocation

score.json

@@ -0,0 +1,3 @@
+{
+  "score": 4
+}

src/crewai/agent.py

@@ -225,6 +225,7 @@ def execute_task(
         task: Task,
         context: Optional[str] = None,
         tools: Optional[List[BaseTool]] = None,
+        recursion_depth: int = 0,
     ) -> str:
         """Execute a task with the agent.
 

src/crewai/agents/agent_adapters/langgraph/langgraph_adapter.py

@@ -1,4 +1,4 @@
-from typing import Any, AsyncIterable, Dict, List, Optional
+from typing import Any, Dict, List, Optional
 
 from pydantic import Field, PrivateAttr
 
@@ -22,7 +22,6 @@
 )
 
 try:
-    from langchain_core.messages import ToolMessage
     from langgraph.checkpoint.memory import MemorySaver
     from langgraph.prebuilt import create_react_agent
 
@@ -126,6 +125,7 @@ def execute_task(
         task: Any,
         context: Optional[str] = None,
         tools: Optional[List[BaseTool]] = None,
+        recursion_depth: int = 0,
     ) -> str:
         """Execute a task using the LangGraph workflow."""
         self.create_agent_executor(tools)

src/crewai/agents/agent_adapters/langgraph/structured_output_converter.py

@@ -74,7 +74,7 @@ def post_process_result(self, result: str) -> str:
                         # Validate it's proper JSON
                         json.loads(extracted)
                         return extracted
-                    except:
+                    except json.JSONDecodeError:
                         pass
 
         return result

src/crewai/agents/agent_adapters/openai_agents/openai_adapter.py

@@ -86,6 +86,7 @@ def execute_task(
         task: Any,
         context: Optional[str] = None,
         tools: Optional[List[BaseTool]] = None,
+        recursion_depth: int = 0,
     ) -> str:
         """Execute a task using the OpenAI Assistant"""
         self._converter_adapter.configure_structured_output(task)

src/crewai/agents/agent_builder/base_agent.py

@@ -25,7 +25,7 @@
 from crewai.tools.base_tool import BaseTool, Tool
 from crewai.utilities import I18N, Logger, RPMController
 from crewai.utilities.config import process_config
-from crewai.utilities.converter import Converter
+# Removed unused import: from crewai.utilities.converter import Converter
 from crewai.utilities.string_utils import interpolate_only
 
 T = TypeVar("T", bound="BaseAgent")
@@ -254,6 +254,7 @@ def execute_task(
         task: Any,
         context: Optional[str] = None,
         tools: Optional[List[BaseTool]] = None,
+        recursion_depth: int = 0,
     ) -> str:
         pass
 

src/crewai/agents/agent_builder/utilities/base_output_converter.py

@@ -1,5 +1,5 @@
 from abc import ABC, abstractmethod
-from typing import Any, Optional
+from typing import Any
 
 from pydantic import BaseModel, Field
 

src/crewai/agents/crew_agent_executor.py

@@ -1,5 +1,3 @@
-import json
-import re
 from typing import Any, Callable, Dict, List, Optional, Union
 
 from crewai.agents.agent_builder.base_agent import BaseAgent

src/crewai/cli/run_crew.py

@@ -1,6 +1,5 @@
 import subprocess
 from enum import Enum
-from typing import List, Optional
 
 import click
 from packaging import version

src/crewai/flow/flow_visualizer.py

@@ -1,14 +1,13 @@
 # flow_visualizer.py
 
 import os
-from pathlib import Path
 
 from pyvis.network import Network
 
 from crewai.flow.config import COLORS, NODE_STYLES
 from crewai.flow.html_template_handler import HTMLTemplateHandler
 from crewai.flow.legend_generator import generate_legend_items_html, get_legend_items
-from crewai.flow.path_utils import safe_path_join, validate_path_exists
+from crewai.flow.path_utils import safe_path_join
 from crewai.flow.utils import calculate_node_levels
 from crewai.flow.visualization_utils import (
     add_edges,

src/crewai/flow/html_template_handler.py

@@ -1,8 +1,7 @@
 import base64
 import re
-from pathlib import Path
 
-from crewai.flow.path_utils import safe_path_join, validate_path_exists
+from crewai.flow.path_utils import validate_path_exists
 
 
 class HTMLTemplateHandler:

src/crewai/flow/path_utils.py

@@ -5,7 +5,6 @@
 traversal attacks and ensure paths remain within allowed boundaries.
 """
 
-import os
 from pathlib import Path
 from typing import List, Union
 

src/crewai/flow/utils.py

@@ -17,7 +17,7 @@
 import inspect
 import textwrap
 from collections import defaultdict, deque
-from typing import Any, Deque, Dict, List, Optional, Set, Union
+from typing import Any, Deque, Dict, List, Optional, Set
 
 
 def get_possible_return_constants(function: Any) -> Optional[List[str]]:

src/crewai/flow/visualization_utils.py

@@ -17,7 +17,7 @@
 
 import ast
 import inspect
-from typing import Any, Dict, List, Optional, Tuple, Union
+from typing import Any, Dict, List, Tuple, Union
 
 from .utils import (
     build_ancestor_dict,

src/crewai/knowledge/source/excel_knowledge_source.py

@@ -1,6 +1,5 @@
 from pathlib import Path
-from typing import Dict, Iterator, List, Optional, Union
-from urllib.parse import urlparse
+from typing import Dict, List, Optional, Union
 
 from pydantic import Field, field_validator
 

src/crewai/lite_agent.py

@@ -1,6 +1,5 @@
 import asyncio
 import uuid
-from datetime import datetime
 from typing import Any, Callable, Dict, List, Optional, Type, Union, cast
 
 from pydantic import BaseModel, Field, InstanceOf, PrivateAttr, model_validator
@@ -35,7 +34,7 @@
     render_text_description_and_args,
     show_agent_logs,
 )
-from crewai.utilities.converter import convert_to_model, generate_model_description
+from crewai.utilities.converter import generate_model_description
 from crewai.utilities.events.agent_events import (
     LiteAgentExecutionCompletedEvent,
     LiteAgentExecutionErrorEvent,

src/crewai/llm.py

@@ -56,16 +56,11 @@
 
 
 class FilteredStream(io.TextIOBase):
-    _lock = None
-
     def __init__(self, original_stream: TextIO):
         self._original_stream = original_stream
         self._lock = threading.Lock()
 
     def write(self, s: str) -> int:
-        if not self._lock:
-            self._lock = threading.Lock()
-
         with self._lock:
             # Filter out extraneous messages from LiteLLM
             if (

src/crewai/llms/base_llm.py

@@ -1,5 +1,5 @@
 from abc import ABC, abstractmethod
-from typing import Any, Callable, Dict, List, Optional, Union
+from typing import Any, Dict, List, Optional, Union
 
 
 class BaseLLM(ABC):

src/crewai/security/security_config.py

@@ -10,7 +10,7 @@
 in CrewAI applications.
 """
 
-from typing import Any, Dict, Optional
+from typing import Any, Dict
 
 from pydantic import BaseModel, ConfigDict, Field, model_validator
 

src/crewai/tasks/llm_guardrail.py

@@ -1,10 +1,9 @@
-from typing import Any, Optional, Tuple
+from typing import Any, Tuple
 
 from pydantic import BaseModel, Field
 
 from crewai.agent import Agent, LiteAgentOutput
 from crewai.llm import LLM
-from crewai.task import Task
 from crewai.tasks.task_output import TaskOutput
 
 

src/crewai/tools/agent_tools/add_image_tool.py

@@ -1,4 +1,4 @@
-from typing import Dict, Optional, Union
+from typing import Optional
 
 from pydantic import BaseModel, Field
 

src/crewai/tools/agent_tools/agent_tools.py

@@ -1,3 +1,5 @@
+from typing import List, Set
+
 from crewai.agents.agent_builder.base_agent import BaseAgent
 from crewai.tools.base_tool import BaseTool
 from crewai.utilities import I18N
@@ -22,11 +24,33 @@ def tools(self) -> list[BaseTool]:
             i18n=self.i18n,
             description=self.i18n.tools("delegate_work").format(coworkers=coworkers),  # type: ignore
         )
+        delegate_tool._agent_tools = self._get_all_agent_tools()
 
         ask_tool = AskQuestionTool(
             agents=self.agents,
             i18n=self.i18n,
             description=self.i18n.tools("ask_question").format(coworkers=coworkers),  # type: ignore
         )
+        ask_tool._agent_tools = self._get_all_agent_tools()
 
         return [delegate_tool, ask_tool]
+
+    def _get_all_agent_tools(self) -> list[BaseTool]:
+        """
+        Get all tools from all agents for recursive invocation.
+
+        Returns:
+            list[BaseTool]: A deduplicated list of all tools from all agents.
+        """
+        seen_tools: Set[int] = set()
+        unique_tools: List[BaseTool] = []
+
+        for agent in self.agents:
+            if agent.tools:
+                for tool in agent.tools:
+                    tool_id = id(tool)
+                    if tool_id not in seen_tools:
+                        seen_tools.add(tool_id)
+                        unique_tools.append(tool)
+
+        return unique_tools

src/crewai/tools/agent_tools/ask_question_tool.py

@@ -1,8 +1,9 @@
-from typing import Optional
+from typing import List, Optional
 
 from pydantic import BaseModel, Field
 
 from crewai.tools.agent_tools.base_agent_tools import BaseAgentTool
+from crewai.tools.base_tool import BaseTool
 
 
 class AskQuestionToolSchema(BaseModel):
@@ -16,6 +17,7 @@ class AskQuestionTool(BaseAgentTool):
 
     name: str = "Ask question to coworker"
     args_schema: type[BaseModel] = AskQuestionToolSchema
+    _agent_tools: Optional[List[BaseTool]] = None
 
     def _run(
         self,
@@ -25,4 +27,5 @@ def _run(
         **kwargs,
     ) -> str:
         coworker = self._get_coworker(coworker, **kwargs)
-        return self._execute(coworker, question, context)
+        tools = self._get_tools(**kwargs)
+        return self._execute(coworker, question, context, tools)

src/crewai/tools/agent_tools/base_agent_tools.py

@@ -1,5 +1,5 @@
 import logging
-from typing import Optional
+from typing import List, Optional
 
 from pydantic import Field
 
@@ -18,6 +18,7 @@ class BaseAgentTool(BaseTool):
     i18n: I18N = Field(
         default_factory=I18N, description="Internationalization settings"
     )
+    MAX_RECURSION_DEPTH: int = 5
 
     def sanitize_agent_name(self, name: str) -> str:
         """
@@ -46,11 +47,22 @@ def _get_coworker(self, coworker: Optional[str], **kwargs) -> Optional[str]:
                 coworker = coworker[1:-1].split(",")[0]
         return coworker
 
+    def _get_tools(self, **kwargs) -> Optional[List[BaseTool]]:
+        """
+        Get tools from instance or kwargs.
+
+        Returns:
+            Optional[List[BaseTool]]: The tools to use for recursive invocation.
+        """
+        return getattr(self, "_agent_tools", None) or kwargs.get("tools")
+
     def _execute(
         self,
         agent_name: Optional[str],
         task: str,
-        context: Optional[str] = None
+        context: Optional[str] = None,
+        tools: Optional[List[BaseTool]] = None,
+        recursion_depth: int = 0,
     ) -> str:
         """
         Execute delegation to an agent with case-insensitive and whitespace-tolerant matching.
@@ -59,11 +71,25 @@ def _execute(
             agent_name: Name/role of the agent to delegate to (case-insensitive)
             task: The specific question or task to delegate
             context: Optional additional context for the task execution
+            tools: Optional tools to pass to the delegated agent for recursive invocation
+            recursion_depth: Current recursion depth to prevent infinite loops
 
         Returns:
             str: The execution result from the delegated agent or an error message
                  if the agent cannot be found
         """
+        if tools is not None and not all(isinstance(tool, BaseTool) for tool in tools):
+            return self.i18n.errors("agent_tool_execution_error").format(
+                agent_role="unknown",
+                error="Invalid tools provided: all tools must inherit from BaseTool",
+            )
+
+        if recursion_depth >= self.MAX_RECURSION_DEPTH:
+            return self.i18n.errors("agent_tool_execution_error").format(
+                agent_role="unknown",
+                error=f"Maximum recursion depth ({self.MAX_RECURSION_DEPTH}) exceeded",
+            )
+
         try:
             if agent_name is None:
                 agent_name = ""
@@ -82,12 +108,12 @@ def _execute(
             available_agents = [agent.role for agent in self.agents]
             logger.debug(f"Available agents: {available_agents}")
 
-            agent = [  # type: ignore # Incompatible types in assignment (expression has type "list[BaseAgent]", variable has type "str | None")
+            matching_agents = [
                 available_agent
                 for available_agent in self.agents
                 if self.sanitize_agent_name(available_agent.role) == sanitized_name
             ]
-            logger.debug(f"Found {len(agent)} matching agents for role '{sanitized_name}'")
+            logger.debug(f"Found {len(matching_agents)} matching agents for role '{sanitized_name}'")
         except (AttributeError, ValueError) as e:
             # Handle specific exceptions that might occur during role name processing
             return self.i18n.errors("agent_tool_unexisting_coworker").format(
@@ -97,7 +123,7 @@ def _execute(
                 error=str(e)
             )
 
-        if not agent:
+        if not matching_agents:
             # No matching agent found after sanitization
             return self.i18n.errors("agent_tool_unexisting_coworker").format(
                 coworkers="\n".join(
@@ -106,16 +132,20 @@ def _execute(
                 error=f"No agent found with role '{sanitized_name}'"
             )
 
-        agent = agent[0]
+        agent = matching_agents[0]
         try:
+            logger.debug(f"Executing task with {len(tools) if tools else 0} tools at recursion depth {recursion_depth}")
             task_with_assigned_agent = Task(
                 description=task,
                 agent=agent,
                 expected_output=agent.i18n.slice("manager_request"),
                 i18n=agent.i18n,
+                tools=tools,
             )
             logger.debug(f"Created task for agent '{self.sanitize_agent_name(agent.role)}': {task}")
-            return agent.execute_task(task_with_assigned_agent, context)
+            return agent.execute_task(
+                task_with_assigned_agent, context, tools, recursion_depth + 1
+            )
         except Exception as e:
             # Handle task creation or execution errors
             return self.i18n.errors("agent_tool_execution_error").format(