fix: #3036 parameter filtering for CrewAI functions with **kwargs

Merge #3037

fix: [#3036](#3036)

- Fix FunctionTool parameter filtering to support CrewAI-style tools
- Functions with **kwargs now receive all parameters except 'self' and 'tool_context'
- Maintains backward compatibility with explicit parameter functions
- Add comprehensive tests for **kwargs functionality

Fixes parameter filtering issue where CrewAI tools using **kwargs pattern would receive empty parameter dictionaries, causing search_query and other parameters to be None.

#non-breaking

COPYBARA_INTEGRATE_REVIEW=#3037 from omarcevi:fix/function-tool-kwargs-parameter-filtering 012bbfc
PiperOrigin-RevId: 825275686

Author: omarcevi

contributing/samples/crewai_tool_kwargs/README.md

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+# CrewAI Tool **kwargs Parameter Handling
+
+This sample demonstrates how `CrewaiTool` correctly handles tools with
+`**kwargs` parameters, which is a common pattern in CrewAI tools.
+
+## What This Sample Demonstrates
+
+### Key Feature: **kwargs Parameter Passing
+
+CrewAI tools often accept arbitrary parameters via `**kwargs`:
+
+```python
+def _run(self, query: str, **kwargs) -> str:
+    # Extra parameters are passed through kwargs
+    category = kwargs.get('category')
+    date_range = kwargs.get('date_range')
+    limit = kwargs.get('limit')
+```
+
+The `CrewaiTool` wrapper detects this pattern and passes all parameters through
+(except framework-managed ones like `self` and `tool_context`).
+
+### Contrast with Regular Tools
+
+For comparison, tools without `**kwargs` only accept explicitly declared
+parameters:
+
+```python
+def _run(self, query: str, category: str) -> str:
+```
+
+## Prerequisites
+
+### Required: CrewAI Tools (Python 3.10+)
+
+```bash
+pip install 'crewai-tools>=0.2.0'
+```
+
+### Required: API Key
+
+```bash
+export GOOGLE_API_KEY="your-api-key-here"
+# OR
+export GOOGLE_GENAI_API_KEY="your-api-key-here"
+```
+
+## Running the Sample
+
+### Option 1: Run the Happy Path Test
+
+```bash
+cd contributing/samples/crewai_tool_kwargs
+python main.py
+```
+
+**Expected output:**
+```
+============================================================
+CrewAI Tool **kwargs Parameter Test
+============================================================
+
+🧪 Test 1: Basic search (no extra parameters)
+User: Search for Python tutorials
+Agent: [Uses tool and returns results]
+
+🧪 Test 2: Search with filters (**kwargs test)
+User: Search for machine learning articles, filtered by...
+Agent: [Uses tool with category, date_range, and limit parameters]
+
+============================================================
+✅ Happy path test completed successfully!
+============================================================
+```
+
+## What Gets Tested
+
+✅ **CrewAI tool integration** - Wrapping a CrewAI BaseTool with ADK
+✅ **Basic parameters** - Required `query` parameter passes correctly
+✅ ****kwargs passing** - Extra parameters (category, date_range, limit) pass
+   through
+✅ **End-to-end execution** - Tool executes and returns results to agent
+
+## Code Structure
+
+```
+crewai_tool_kwargs/
+├── __init__.py       # Module initialization
+├── agent.py          # Agent with CrewAI tool
+├── main.py           # Happy path test
+└── README.md         # This file
+```
+
+### Key Files
+
+**agent.py:**
+
+- Defines `CustomSearchTool` (CrewAI BaseTool with **kwargs)
+- Wraps it with `CrewaiTool`
+- Creates agent with the wrapped tool
+
+**main.py:**
+
+- Test 1: Basic search (no extra params)
+- Test 2: Search with filters (tests **kwargs)
+
+## How It Works
+
+1. **CrewAI Tool Definition** (`agent.py`):
+   ```python
+   class CustomSearchTool(BaseTool):
+       def _run(self, query: str, **kwargs) -> str:
+           # kwargs receives: category, date_range, limit, etc.
+   ```
+
+2. **ADK Wrapping** (`agent.py`):
+   ```python
+   adk_search_tool = CrewaiTool(
+       crewai_search_tool,
+       name="search_with_filters",
+       description="..."
+   )
+   ```
+
+3. **LLM Function Calling** (`main.py`):
+   - LLM sees the tool in function calling format
+   - LLM calls with: `{query: "...", category: "...", date_range: "...", limit: 10}`
+   - CrewaiTool passes ALL parameters to `**kwargs`
+
+4. **Tool Execution**:
+   - `query` → positional parameter
+   - `category`, `date_range`, `limit` → collected in `**kwargs`
+   - Tool logic uses all parameters
+
+## Troubleshooting
+
+### ImportError: No module named 'crewai'
+
+```bash
+pip install 'crewai-tools>=0.2.0'
+```
+
+### Python Version Error
+
+CrewAI requires Python 3.10+:
+
+```bash
+python --version  # Should be 3.10 or higher
+```
+
+### Missing API Key
+
+```bash
+export GOOGLE_API_KEY="your-key-here"
+```
+
+## Related
+
+- Parent class: `FunctionTool` - Base class for all function-based tools
+- Unit tests: `tests/unittests/tools/test_crewai_tool.py`

contributing/samples/crewai_tool_kwargs/__init__.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from . import agent

contributing/samples/crewai_tool_kwargs/agent.py

@@ -0,0 +1,112 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Sample demonstrating CrewAI tool with **kwargs parameter handling.
+
+This sample shows how CrewaiTool correctly passes arbitrary parameters
+through **kwargs, which is a common pattern in CrewAI tools.
+"""
+
+from typing import Optional
+
+from crewai.tools import BaseTool
+from google.adk import Agent
+from google.adk.tools.crewai_tool import CrewaiTool
+from pydantic import BaseModel
+from pydantic import Field
+
+
+class SearchInput(BaseModel):
+  """Input schema for the search tool."""
+
+  query: str = Field(..., description="The search query string")
+  category: Optional[str] = Field(
+      None, description="Filter by category (e.g., 'technology', 'science')"
+  )
+  date_range: Optional[str] = Field(
+      None, description="Filter by date range (e.g., 'last_week', '2024')"
+  )
+  limit: Optional[int] = Field(
+      None, description="Limit the number of results (e.g., 10, 20)"
+  )
+
+
+class CustomSearchTool(BaseTool):
+  """A custom CrewAI tool that accepts arbitrary search parameters via **kwargs.
+
+  This demonstrates the key CrewAI tool pattern where tools accept
+  flexible parameters through **kwargs.
+  """
+
+  name: str = "custom_search"
+  description: str = (
+      "Search for information with flexible filtering options. "
+      "Accepts a query and optional filter parameters like category, "
+      "date_range, limit, etc."
+  )
+  args_schema: type[BaseModel] = SearchInput
+
+  def _run(self, query: str, **kwargs) -> str:
+    """Execute search with arbitrary filter parameters.
+
+    Args:
+      query: The search query string.
+      **kwargs: Additional filter parameters like category, date_range, limit.
+
+    Returns:
+      A formatted string showing the query and applied filters.
+    """
+    result_parts = [f"Searching for: '{query}'"]
+
+    if kwargs:
+      result_parts.append("Applied filters:")
+      for key, value in kwargs.items():
+        result_parts.append(f"  - {key}: {value}")
+    else:
+      result_parts.append("No additional filters applied.")
+
+    # Simulate search results
+    result_parts.append(f"\nFound 3 results matching your criteria.")
+
+    return "\n".join(result_parts)
+
+
+crewai_search_tool = CustomSearchTool()
+
+# Wrap it with ADK's CrewaiTool
+adk_search_tool = CrewaiTool(
+    crewai_search_tool,
+    name="search_with_filters",
+    description=(
+        "Search for information with optional filters like category, "
+        "date_range, or limit"
+    ),
+)
+
+root_agent = Agent(
+    model="gemini-2.0-flash",
+    name="search_agent",
+    description="An agent that can search with flexible filtering options",
+    instruction="""
+      You are a helpful search assistant.
+      When users ask you to search, use the search_with_filters tool.
+      You can pass additional parameters like:
+      - category: to filter by category (e.g., "technology", "science")
+      - date_range: to filter by date (e.g., "last_week", "2024")
+      - limit: to limit the number of results (e.g., 10, 20)
+
+      Always acknowledge what filters you're applying.
+    """,
+    tools=[adk_search_tool],
+)

contributing/samples/crewai_tool_kwargs/main.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Happy path test for CrewAI tool with **kwargs parameter handling.
+
+This demonstrates that CrewaiTool correctly passes arbitrary parameters
+through **kwargs to the underlying CrewAI tool.
+"""
+
+import asyncio
+
+import agent
+from dotenv import load_dotenv
+from google.adk.cli.utils import logs
+from google.adk.runners import InMemoryRunner
+from google.genai import types
+
+load_dotenv(override=True)
+logs.log_to_tmp_folder()
+
+
+async def main():
+  """Run happy path test demonstrating **kwargs parameter passing."""
+  app_name = "crewai_kwargs_test"
+  user_id = "test_user"
+
+  runner = InMemoryRunner(
+      agent=agent.root_agent,
+      app_name=app_name,
+  )
+
+  session = await runner.session_service.create_session(
+      app_name=app_name, user_id=user_id
+  )
+
+  print("=" * 60)
+  print("CrewAI Tool **kwargs Parameter Test")
+  print("=" * 60)
+
+  # Test 1: Simple search without extra parameters
+  print("\n🧪 Test 1: Basic search (no extra parameters)")
+  print("-" * 60)
+  content1 = types.Content(
+      role="user",
+      parts=[types.Part.from_text(text="Search for Python tutorials")],
+  )
+  print(f"User: {content1.parts[0].text}")
+
+  async for event in runner.run_async(
+      user_id=user_id,
+      session_id=session.id,
+      new_message=content1,
+  ):
+    if event.content.parts and event.content.parts[0].text:
+      print(f"Agent: {event.content.parts[0].text}")
+
+  # Test 2: Search with extra parameters (testing **kwargs)
+  print("\n🧪 Test 2: Search with filters (**kwargs test)")
+  print("-" * 60)
+  content2 = types.Content(
+      role="user",
+      parts=[
+          types.Part.from_text(
+              text=(
+                  "Search for machine learning articles, filtered by category"
+                  " 'technology', date_range 'last_month', and limit to 10"
+                  " results"
+              )
+          )
+      ],
+  )
+  print(f"User: {content2.parts[0].text}")
+
+  async for event in runner.run_async(
+      user_id=user_id,
+      session_id=session.id,
+      new_message=content2,
+  ):
+    if event.content.parts and event.content.parts[0].text:
+      print(f"Agent: {event.content.parts[0].text}")
+
+  # Verify success
+  print("\n" + "=" * 60)
+  print("✅ Happy path test completed successfully!")
+  print("=" * 60)
+  print("\nVerified behaviors:")
+  print("  ✅ CrewAI tool integrated with ADK agent")
+  print("  ✅ Basic parameters passed correctly")
+  print("  ✅ Extra parameters passed through **kwargs")
+  print("  ✅ Tool executed and returned results")
+
+
+if __name__ == "__main__":
+  asyncio.run(main())