Introduce more fine control over delegation

src/crewai/agent.py

@@ -1,7 +1,7 @@
 import re
 import shutil
 import subprocess
-from typing import Any, Dict, List, Literal, Optional, Sequence, Union
+from typing import Any, Dict, List, Literal, Optional, Sequence, Union, cast
 
 from pydantic import Field, InstanceOf, PrivateAttr, model_validator
 
@@ -50,6 +50,7 @@ class Agent(BaseAgent):
             max_rpm: Maximum number of requests per minute for the agent execution to be respected.
             verbose: Whether the agent execution should be in verbose mode.
             allow_delegation: Whether the agent is allowed to delegate tasks to other agents.
+            delegate_to: List of agents this agent can delegate to. If None and allow_delegation is True, can delegate to all agents.
             tools: Tools at agents disposal
             step_callback: Callback to be executed after each step of the agent execution.
             knowledge_sources: Knowledge sources for the agent.
@@ -342,10 +343,17 @@ def create_agent_executor(
             callbacks=[TokenCalcHandler(self._token_process)],
         )
 
-    def get_delegation_tools(self, agents: List[BaseAgent]):
-        agent_tools = AgentTools(agents=agents)
-        tools = agent_tools.tools()
-        return tools
+    def get_delegation_tools(self, agents: Sequence[BaseAgent]) -> Sequence[BaseTool]:
+        # If delegate_to is specified, use those agents instead of all agents
+        agents_to_use: List[BaseAgent]
+        if self.delegate_to is not None:
+            agents_to_use = cast(List[BaseAgent], list(self.delegate_to))
+        else:
+            agents_to_use = list(agents)  # Convert to list to match expected type
+
+        agent_tools = AgentTools(agents=agents_to_use)
+        delegation_tools = agent_tools.tools()
+        return delegation_tools
 
     def get_multimodal_tools(self) -> Sequence[BaseTool]:
         from crewai.tools.agent_tools.add_image_tool import AddImageTool

src/crewai/agents/agent_builder/base_agent.py

@@ -2,7 +2,7 @@
 from abc import ABC, abstractmethod
 from copy import copy as shallow_copy
 from hashlib import md5
-from typing import Any, Dict, List, Optional, TypeVar
+from typing import Any, Dict, List, Optional, Sequence, TypeVar
 
 from pydantic import (
     UUID4,
@@ -42,6 +42,7 @@ class BaseAgent(ABC, BaseModel):
         verbose (bool): Verbose mode for the Agent Execution.
         max_rpm (Optional[int]): Maximum number of requests per minute for the agent execution.
         allow_delegation (bool): Allow delegation of tasks to agents.
+        delegate_to (Optional[List["BaseAgent"]]): List of agents this agent can delegate to. If None and allow_delegation is True, can delegate to all agents.
         tools (Optional[List[Any]]): Tools at the agent's disposal.
         max_iter (int): Maximum iterations for an agent to execute a task.
         agent_executor (InstanceOf): An instance of the CrewAgentExecutor class.
@@ -63,7 +64,7 @@ class BaseAgent(ABC, BaseModel):
             Abstract method to create an agent executor.
         _parse_tools(tools: List[BaseTool]) -> List[Any]:
             Abstract method to parse tools.
-        get_delegation_tools(agents: List["BaseAgent"]):
+        get_delegation_tools(agents: Sequence["BaseAgent"]) -> Sequence[BaseTool]:
             Abstract method to set the agents task tools for handling delegation and question asking to other agents in crew.
         get_output_converter(llm, model, instructions):
             Abstract method to get the converter class for the agent to create json/pydantic outputs.
@@ -113,6 +114,10 @@ class BaseAgent(ABC, BaseModel):
         default=False,
         description="Enable agent to delegate and ask questions among each other.",
     )
+    delegate_to: Optional[List["BaseAgent"]] = Field(
+        default=None,
+        description="List of agents this agent can delegate to. If None and allow_delegation is True, can delegate to all agents.",
+    )
     tools: Optional[List[BaseTool]] = Field(
         default_factory=list, description="Tools at agents' disposal"
     )
@@ -258,7 +263,7 @@ def _parse_tools(self, tools: List[BaseTool]) -> List[BaseTool]:
         pass
 
     @abstractmethod
-    def get_delegation_tools(self, agents: List["BaseAgent"]) -> List[BaseTool]:
+    def get_delegation_tools(self, agents: Sequence["BaseAgent"]) -> Sequence[BaseTool]:
         """Set the task tools that init BaseAgenTools class."""
         pass
 
@@ -285,6 +290,7 @@ def copy(self: T) -> T:  # type: ignore # Signature of "copy" incompatible with
             "knowledge_sources",
             "knowledge_storage",
             "knowledge",
+            "delegate_to",
         }
 
         # Copy llm
@@ -310,6 +316,10 @@ def copy(self: T) -> T:  # type: ignore # Signature of "copy" incompatible with
                 copied_source.storage = shared_storage
                 existing_knowledge_sources.append(copied_source)
 
+        existing_delegate_to = None
+        if self.delegate_to:
+            existing_delegate_to = list(self.delegate_to)
+
         copied_data = self.model_dump(exclude=exclude)
         copied_data = {k: v for k, v in copied_data.items() if v is not None}
         copied_agent = type(self)(
@@ -319,6 +329,7 @@ def copy(self: T) -> T:  # type: ignore # Signature of "copy" incompatible with
             knowledge_sources=existing_knowledge_sources,
             knowledge=copied_knowledge,
             knowledge_storage=copied_knowledge_storage,
+            delegate_to=existing_delegate_to,
         )
 
         return copied_agent

src/crewai/crew.py

@@ -6,7 +6,7 @@
 from concurrent.futures import Future
 from copy import copy as shallow_copy
 from hashlib import md5
-from typing import Any, Callable, Dict, List, Optional, Set, Tuple, Union
+from typing import Any, Callable, Dict, List, Optional, Sequence, Set, Tuple, Union
 
 from pydantic import (
     UUID4,
@@ -36,6 +36,7 @@
 from crewai.task import Task
 from crewai.tasks.conditional_task import ConditionalTask
 from crewai.tasks.task_output import TaskOutput
+from crewai.tools import BaseTool
 from crewai.tools.agent_tools.agent_tools import AgentTools
 from crewai.tools.base_tool import Tool
 from crewai.types.usage_metrics import UsageMetrics
@@ -759,22 +760,27 @@ def _run_hierarchical_process(self) -> CrewOutput:
     def _create_manager_agent(self):
         i18n = I18N(prompt_file=self.prompt_file)
         if self.manager_agent is not None:
+            # Ensure delegation is enabled for the manager agent
             self.manager_agent.allow_delegation = True
+
+            # Set the delegate_to property to all agents in the crew
+            # If delegate_to is already set, it will be used instead of all agents
+            if self.manager_agent.delegate_to is None:
+                self.manager_agent.delegate_to = self.agents
+
             manager = self.manager_agent
-            if manager.tools is not None and len(manager.tools) > 0:
-                self._logger.log(
-                    "warning", "Manager agent should not have tools", color="orange"
-                )
-                manager.tools = []
-                raise Exception("Manager agent should not have tools")
         else:
             self.manager_llm = create_llm(self.manager_llm)
+            # Create delegation tools
+            delegation_tools = AgentTools(agents=self.agents).tools()
+
             manager = Agent(
                 role=i18n.retrieve("hierarchical_manager_agent", "role"),
                 goal=i18n.retrieve("hierarchical_manager_agent", "goal"),
                 backstory=i18n.retrieve("hierarchical_manager_agent", "backstory"),
-                tools=AgentTools(agents=self.agents).tools(),
+                tools=delegation_tools,
                 allow_delegation=True,
+                delegate_to=self.agents,
                 llm=self.manager_llm,
                 verbose=self.verbose,
             )
@@ -818,8 +824,8 @@ def _execute_tasks(
                 )
 
             # Determine which tools to use - task tools take precedence over agent tools
-            tools_for_task = task.tools or agent_to_use.tools or []
-            tools_for_task = self._prepare_tools(agent_to_use, task, tools_for_task)
+            initial_tools = task.tools or agent_to_use.tools or []
+            prepared_tools = self._prepare_tools(agent_to_use, task, initial_tools)
 
             self._log_task_start(task, agent_to_use.role)
 
@@ -838,7 +844,7 @@ def _execute_tasks(
                 future = task.execute_async(
                     agent=agent_to_use,
                     context=context,
-                    tools=tools_for_task,
+                    tools=prepared_tools,
                 )
                 futures.append((task, future, task_index))
             else:
@@ -850,7 +856,7 @@ def _execute_tasks(
                 task_output = task.execute_sync(
                     agent=agent_to_use,
                     context=context,
-                    tools=tools_for_task,
+                    tools=prepared_tools,
                 )
                 task_outputs.append(task_output)
                 self._process_task_result(task, task_output)
@@ -888,8 +894,8 @@ def _handle_conditional_task(
         return None
 
     def _prepare_tools(
-        self, agent: BaseAgent, task: Task, tools: List[Tool]
-    ) -> List[Tool]:
+        self, agent: BaseAgent, task: Task, tools: Sequence[BaseTool]
+    ) -> list[BaseTool]:
         # Add delegation tools if agent allows delegation
         if agent.allow_delegation:
             if self.process == Process.hierarchical:
@@ -904,22 +910,24 @@ def _prepare_tools(
                 tools = self._add_delegation_tools(task, tools)
 
         # Add code execution tools if agent allows code execution
-        if agent.allow_code_execution:
+        if hasattr(agent, "allow_code_execution") and getattr(
+            agent, "allow_code_execution", False
+        ):
             tools = self._add_code_execution_tools(agent, tools)
 
-        if agent and agent.multimodal:
+        if hasattr(agent, "multimodal") and getattr(agent, "multimodal", False):
             tools = self._add_multimodal_tools(agent, tools)
 
-        return tools
+        return list(tools)
 
     def _get_agent_to_use(self, task: Task) -> Optional[BaseAgent]:
         if self.process == Process.hierarchical:
             return self.manager_agent
         return task.agent
 
     def _merge_tools(
-        self, existing_tools: List[Tool], new_tools: List[Tool]
-    ) -> List[Tool]:
+        self, existing_tools: Sequence[BaseTool], new_tools: Sequence[BaseTool]
+    ) -> Sequence[BaseTool]:
         """Merge new tools into existing tools list, avoiding duplicates by tool name."""
         if not new_tools:
             return existing_tools
@@ -936,21 +944,42 @@ def _merge_tools(
         return tools
 
     def _inject_delegation_tools(
-        self, tools: List[Tool], task_agent: BaseAgent, agents: List[BaseAgent]
+        self,
+        tools: Sequence[BaseTool],
+        task_agent: BaseAgent,
+        agents: Sequence[BaseAgent],
     ):
         delegation_tools = task_agent.get_delegation_tools(agents)
         return self._merge_tools(tools, delegation_tools)
 
-    def _add_multimodal_tools(self, agent: BaseAgent, tools: List[Tool]):
-        multimodal_tools = agent.get_multimodal_tools()
-        return self._merge_tools(tools, multimodal_tools)
+    def _add_multimodal_tools(
+        self, agent: BaseAgent, tools: Sequence[BaseTool]
+    ) -> Sequence[BaseTool]:
+        if hasattr(agent, "get_multimodal_tools"):
+            multimodal_tools = getattr(agent, "get_multimodal_tools")()
+            return self._merge_tools(tools, multimodal_tools)
+        return tools
 
-    def _add_code_execution_tools(self, agent: BaseAgent, tools: List[Tool]):
-        code_tools = agent.get_code_execution_tools()
-        return self._merge_tools(tools, code_tools)
+    def _add_code_execution_tools(
+        self, agent: BaseAgent, tools: Sequence[BaseTool]
+    ) -> Sequence[BaseTool]:
+        if hasattr(agent, "get_code_execution_tools"):
+            code_tools = getattr(agent, "get_code_execution_tools")()
+            return self._merge_tools(tools, code_tools)
+        return tools
+
+    def _add_delegation_tools(
+        self, task: Task, tools: Sequence[BaseTool]
+    ) -> Sequence[BaseTool]:
+        # If the agent has specific agents to delegate to, use those
+        if task.agent and task.agent.delegate_to is not None:
+            agents_for_delegation = task.agent.delegate_to
+        else:
+            # Otherwise use all agents except the current one
+            agents_for_delegation = [
+                agent for agent in self.agents if agent != task.agent
+            ]
 
-    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 = []
@@ -965,7 +994,7 @@ def _log_task_start(self, task: Task, role: str = "None"):
                 task_name=task.name, task=task.description, agent=role, status="started"
             )
 
-    def _update_manager_tools(self, task: Task, tools: List[Tool]):
+    def _update_manager_tools(self, task: Task, tools: Sequence[BaseTool]):
         if self.manager_agent:
             if task.agent:
                 tools = self._inject_delegation_tools(tools, task.agent, [task.agent])

src/crewai/tools/agent_tools/agent_tools.py

@@ -1,3 +1,5 @@
+from typing import List
+
 from crewai.agents.agent_builder.base_agent import BaseAgent
 from crewai.tools.base_tool import BaseTool
 from crewai.utilities import I18N
@@ -9,11 +11,11 @@
 class AgentTools:
     """Manager class for agent-related tools"""
 
-    def __init__(self, agents: list[BaseAgent], i18n: I18N = I18N()):
+    def __init__(self, agents: List[BaseAgent], i18n: I18N = I18N()):
         self.agents = agents
         self.i18n = i18n
 
-    def tools(self) -> list[BaseTool]:
+    def tools(self) -> List[BaseTool]:
         """Get all available agent tools"""
         coworkers = ", ".join([f"{agent.role}" for agent in self.agents])