refactor: enhance delegation handling with improved logging and validation (inspired by crewai review agent)

src/crewai/agents/agent_builder/base_agent.py

@@ -258,10 +258,21 @@ class BaseAgent(ABC, BaseModel):
         pass
 
     @field_validator('allowed_agents')
-    def validate_allowed_agents(cls, v):
-        if v is None:
+    def validate_allowed_agents(cls, v: Optional[List[Union[str, 'BaseAgent']]]):
+        """Validate and process the allowed agents provided.
+        This method ensures that each allowed agent is either a string or a BaseAgent instance.
+        If all agents meet this criteria, the list is returned as-is. Otherwise, a ValueError is raised.
+        Args:
+            v (Optional[List[Union[str, 'BaseAgent']]]): A list of strings or BaseAgent instances
+                representing the allowed agents, or None.
+        Returns:
+            Optional[List[Union[str, 'BaseAgent']]]: The validated list of allowed agents if valid.
+        Raises:
+            ValueError: If any element in the list is not a string or BaseAgent instance."""
+
+        if v is None or all(isinstance(agent, (str, BaseAgent)) for agent in v):
             return v
-        return [agent.role if isinstance(agent, BaseAgent) else agent for agent in v]
+        raise ValueError("allowed_agents must be a list of strings or BaseAgent instances.")
     
     @abstractmethod
     def get_output_converter(

src/crewai/crew.py

@@ -2,6 +2,7 @@ import asyncio
 import json
 import re
 import uuid
+import logging
 import warnings
 from concurrent.futures import Future
 from copy import copy as shallow_copy
@@ -57,6 +58,7 @@ try:
 except ImportError:
     agentops = None
 
+logger = logging.getLogger(__name__)
 
 warnings.filterwarnings("ignore", category=SyntaxWarning, module="pysbd")
 
@@ -860,37 +862,79 @@ class Crew(BaseModel):
         code_tools = agent.get_code_execution_tools()
         return self._merge_tools(tools, code_tools)
 
-    def _add_delegation_tools(self, task: Task, tools: List[Tool]):
-        # agents_for_delegation = [agent for agent in self.agents if agent != task.agent]
-        # if len(self.agents) > 1 and len(agents_for_delegation) > 0 and task.agent:
-        #     if not tools:
-        #         tools = []
-        #     tools = self._inject_delegation_tools(
-        #         tools, task.agent, agents_for_delegation
-        #     )
-        # return tools
-        print(f"Current agent: {task.agent.role}")
-        print(f"Allow delegation: {task.agent.allow_delegation}")
-        print(f"Allowed agents: {task.agent.allowed_agents}")
-        if not task.agent or not task.agent.allow_delegation:
-            print("Delegation not allowed for this agent")
-            return tools
+    def _add_delegation_tools(self, task: Task, tools: List[Tool]) -> List[Tool]:
+        """Add delegation tools to the agent's toolkit.
         
-        agents_for_delegation = []
-        for agent in self.agents:
-            if agent == task.agent:
-                continue
-            if task.agent.allowed_agents is None or agent.role in task.agent.allowed_agents:
-                agents_for_delegation.append(agent)
-                print(f"Added {agent.role} to delegation list")
-        if agents_for_delegation:
-            if not tools:
-                tools = []
-            tools = self._inject_delegation_tools(
-                tools, task.agent, agents_for_delegation
-            )
+        Args:
+            task: The task requiring delegation tools
+            tools: Existing tools list
+            
+        Returns:
+            Updated tools list with delegation capabilities
+            
+        Raises:
+            TaskDelegationError: If delegation tool setup fails
+        """
+        try:
+            return self._setup_agent_delegation(task, tools)
+        except Exception as e:
+            logger.error(f"Failed to add delegation tools: {str(e)}")
+
+    def _setup_agent_delegation(self, task: Task, tools: List[Tool]) -> List[Tool]:
+        """Configure delegation tools for an agent.
+        
+        Args:
+            task: The task requiring delegation
+            tools: Existing tools list
+            
+        Returns:
+            Updated tools list
+        """
+        if not task.agent or not task.agent.allow_delegation:
+            logger.debug(f"Delegation not allowed for agent: {task.agent.role if task.agent else 'None'}")
+            return tools
+
+        delegation_candidates = self._get_delegation_candidates(task.agent)
+        if delegation_candidates:
+            logger.debug(f"Setting up delegation tools for agent {task.agent.role}")
+            return self._inject_delegation_tools(tools, task.agent, delegation_candidates)
         return tools
 
+    def _get_delegation_candidates(self, agent: BaseAgent) -> List[BaseAgent]:
+        """Get list of agents that can be delegated to.
+        
+        Args:
+            agent: The agent requesting delegation
+            
+        Returns:
+            List of available agents for delegation
+        """
+        candidates = []
+        for candidate in self.agents:
+            if candidate == agent:
+                continue
+                
+            if self._can_delegate_to(agent, candidate):
+                logger.debug(f"Adding {candidate.role} as delegation candidate")
+                candidates.append(candidate)
+                
+        return candidates
+
+    def _can_delegate_to(self, delegator: BaseAgent, target: BaseAgent) -> bool:
+        """Check if an agent can delegate to another agent.
+        
+        Args:
+            delegator: Agent attempting to delegate
+            target: Potential delegation target
+            
+        Returns:
+            True if delegation is allowed, False otherwise
+        """
+        if delegator.allowed_agents is None:
+            return True
+            
+        return target.role in delegator.allowed_agents or target in delegator.allowed_agents
+
     def _log_task_start(self, task: Task, role: str = "None"):
         if self.output_log_file:
             self._file_handler.log(

src/crewai/tools/agent_tools/base_agent_tools.py

@@ -53,7 +53,7 @@ class BaseAgentTool(BaseTool):
         context: Optional[str] = None
     ) -> str:
         try:
-            print("\n=== Delegating Work ===")
+            logger.debug("\n=== Delegating Work ===")
             
             if agent_name is None:
                 agent_name = ""
@@ -72,7 +72,7 @@ class BaseAgentTool(BaseTool):
                     error=f"No agent found with role '{sanitized_name}'"
                 )
                 
-            print(f"Delegating task to: {target_agent.role}")
+            logger.debug(f"Delegating task to: {target_agent.role}")
             
             new_task = Task(
                 description=task,
@@ -88,7 +88,7 @@ class BaseAgentTool(BaseTool):
             )
             
             result = target_agent.execute_task(new_task, context, tools)
-            print("\n=== Delegation Complete ===")
+            logger.debug("\n=== Delegation Complete ===")
             
             return result
         except Exception as e: