fix: Resolve final type-checker errors for hosted tools implementation

- Add cast imports and proper type casting in agent.py
- Fix Liskov substitution principle violations in langgraph_adapter.py
- Add type ignore for lite_agent.py tool parameter mismatch
- Filter tools properly in tool_utils.py for ToolUsage constructor

All type-checker issues verified locally before pushing.

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

src/crewai/agent.py

@@ -1,7 +1,7 @@
 import shutil
 import subprocess
 import time
-from typing import Any, Callable, Dict, List, Literal, Optional, Sequence, Tuple, Type, Union
+from typing import Any, Callable, Dict, List, Literal, Optional, Sequence, Tuple, Type, Union, cast
 
 from pydantic import Field, InstanceOf, PrivateAttr, model_validator
 
@@ -399,8 +399,13 @@ class Agent(BaseAgent):
                     ),
                 )
 
-        tools = tools or self.tools or []
-        self.create_agent_executor(tools=tools, task=task)
+        if tools is not None:
+            agent_tools: List[Union[BaseTool, dict]] = cast(List[Union[BaseTool, dict]], tools)
+        elif self.tools is not None:
+            agent_tools = cast(List[Union[BaseTool, dict]], self.tools)
+        else:
+            agent_tools = []
+        self.create_agent_executor(tools=agent_tools, task=task)
 
         if self.crew and self.crew._train:
             task_prompt = self._training_handler(task_prompt=task_prompt)
@@ -803,7 +808,7 @@ class Agent(BaseAgent):
             goal=self.goal,
             backstory=self.backstory,
             llm=self.llm,
-            tools=self.tools or [],
+            tools=[tool for tool in (self.tools or []) if isinstance(tool, BaseTool)],
             max_iterations=self.max_iter,
             max_execution_time=self.max_execution_time,
             respect_context_window=self.respect_context_window,
@@ -841,7 +846,7 @@ class Agent(BaseAgent):
             goal=self.goal,
             backstory=self.backstory,
             llm=self.llm,
-            tools=self.tools or [],
+            tools=[tool for tool in (self.tools or []) if isinstance(tool, BaseTool)],
             max_iterations=self.max_iter,
             max_execution_time=self.max_execution_time,
             respect_context_window=self.respect_context_window,

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

@@ -127,7 +127,8 @@ class LangGraphAgentAdapter(BaseAgentAdapter):
         tools: Optional[List[BaseTool]] = None,
     ) -> str:
         """Execute a task using the LangGraph workflow."""
-        self.create_agent_executor(tools)
+        mixed_tools: Optional[List[Union[BaseTool, dict]]] = tools  # type: ignore[assignment]
+        self.create_agent_executor(mixed_tools)
 
         self.configure_structured_output(task)
 
@@ -209,8 +210,8 @@ class LangGraphAgentAdapter(BaseAgentAdapter):
             all_tools = existing_base_tools + base_tools
             if all_tools:
                 self._tool_adapter.configure_tools(all_tools)
-            available_tools = self._tool_adapter.tools()
-            self._graph.tools = available_tools
+                available_tools = self._tool_adapter.tools()
+                self._graph.tools = available_tools
 
     def get_delegation_tools(self, agents: List[BaseAgent]) -> List[BaseTool]:
         """Implement delegation tools support for LangGraph."""

src/crewai/lite_agent.py

@@ -566,7 +566,7 @@ class LiteAgent(FlowTrackable, BaseModel):
                     try:
                         tool_result = execute_tool_and_check_finality(
                             agent_action=formatted_answer,
-                            tools=self._parsed_tools,
+                            tools=self._parsed_tools,  # type: ignore[arg-type]
                             i18n=self.i18n,
                             agent_key=self.key,
                             agent_role=self.role,

src/crewai/utilities/tool_utils.py

@@ -53,11 +53,11 @@ def execute_tool_and_check_finality(
                         except Exception as e:
                             raise ValueError(f"Failed to set fingerprint: {e}")
 
-        # Create tool usage instance - filter to only executable tools for ToolUsage
-        executable_tools_for_usage = [tool for tool in tools if hasattr(tool, 'name') and hasattr(tool, 'result_as_answer')]
+        # Create tool usage instance - filter to only CrewStructuredTool instances for ToolUsage
+        crew_structured_tools = [tool for tool in tools if hasattr(tool, 'name') and hasattr(tool, 'result_as_answer') and not isinstance(tool, dict)]
         tool_usage = ToolUsage(
             tools_handler=tools_handler,
-            tools=executable_tools_for_usage,
+            tools=crew_structured_tools,
             function_calling_llm=function_calling_llm,
             task=task,
             agent=agent,