litellm/tests/test_litellm/experimental_mcp_client/test_tools.py
Tin Chi Lo 56cda9f674 fix(mcp): sanitize Anthropic tool schemas and stop encoding gateway names
Two review findings, both a chat-vs-messages divergence.

transform_mcp_tool_to_anthropic_tool sent the MCP inputSchema to Anthropic almost
as-is, while the chat path (_map_tool_helper) coerces the type to object, inlines
legacy definitions with unpack_legacy_defs, and allow-lists keys to
AnthropicInputSchema. So a tool whose schema carried $schema, legacy definitions
or oneOf worked on /chat/completions and 400d on /v1/messages; a clean-schema
server hid it. Both paths now run the same sanitize_input_schema_for_anthropic,
extracted next to unpack_legacy_defs so they cannot drift again, and the chat
path is refactored onto it rather than keeping its own copy.

buildMcpToolBlocks percent-encoded the server and toolset names inside
litellm_proxy/mcp/... urls, but the gateway resolves the name with a raw
server_url.split("/")[-1] and never url-decodes, so a name with a space failed
lookup. The already-working chat path does not encode; the shared builder now
matches it.

Tests pin both: reverting the transform to the unfiltered schema fails, and
re-adding encodeURIComponent fails the builder test.
2026-07-17 10:33:28 -07:00

343 lines
12 KiB
Python

import json
import os
import sys
from unittest.mock import AsyncMock, MagicMock
import pytest
sys.path.insert(
0, os.path.abspath("../../..")
) # Adds the parent directory to the system path
from mcp.types import (
CallToolRequestParams,
CallToolResult,
ListToolsResult,
TextContent,
)
from mcp.types import Tool as MCPTool
from litellm.experimental_mcp_client.tools import (
transform_mcp_tool_to_anthropic_tool,
_get_function_arguments,
_normalize_mcp_input_schema,
call_mcp_tool,
call_openai_tool,
load_mcp_tools,
transform_mcp_tool_to_openai_responses_api_tool,
transform_mcp_tool_to_openai_tool,
transform_openai_tool_call_request_to_mcp_tool_call_request,
)
@pytest.fixture
def mock_mcp_tool():
return MCPTool(
name="test_tool",
description="A test tool",
inputSchema={"type": "object", "properties": {"test": {"type": "string"}}},
)
@pytest.fixture
def mock_session():
session = MagicMock()
session.list_tools = AsyncMock()
session.call_tool = AsyncMock()
return session
@pytest.fixture
def mock_list_tools_result():
return ListToolsResult(
tools=[
MCPTool(
name="test_tool",
description="A test tool",
inputSchema={
"type": "object",
"properties": {"test": {"type": "string"}},
},
)
]
)
@pytest.fixture
def mock_mcp_tool_call_result():
return CallToolResult(content=[TextContent(type="text", text="test_output")])
def test_transform_mcp_tool_to_openai_tool(mock_mcp_tool):
openai_tool = transform_mcp_tool_to_openai_tool(mock_mcp_tool)
assert openai_tool["type"] == "function"
assert openai_tool["function"]["name"] == "test_tool"
assert openai_tool["function"]["description"] == "A test tool"
assert openai_tool["function"]["parameters"] == {
"type": "object",
"properties": {"test": {"type": "string"}},
"additionalProperties": False,
}
def testtransform_openai_tool_call_request_to_mcp_tool_call_request(mock_mcp_tool):
openai_tool = {
"function": {"name": "test_tool", "arguments": json.dumps({"test": "value"})}
}
mcp_tool_call_request = transform_openai_tool_call_request_to_mcp_tool_call_request(
openai_tool
)
assert mcp_tool_call_request.name == "test_tool"
assert mcp_tool_call_request.arguments == {"test": "value"}
@pytest.mark.asyncio()
async def test_load_mcp_tools_mcp_format(mock_session, mock_list_tools_result):
mock_session.list_tools.return_value = mock_list_tools_result
result = await load_mcp_tools(mock_session, format="mcp")
assert len(result) == 1
assert isinstance(result[0], MCPTool)
assert result[0].name == "test_tool"
mock_session.list_tools.assert_called_once()
@pytest.mark.asyncio()
async def test_load_mcp_tools_openai_format(mock_session, mock_list_tools_result):
mock_session.list_tools.return_value = mock_list_tools_result
result = await load_mcp_tools(mock_session, format="openai")
assert len(result) == 1
assert result[0]["type"] == "function"
assert result[0]["function"]["name"] == "test_tool"
mock_session.list_tools.assert_called_once()
def test_get_function_arguments():
# Test with string arguments
function = {"arguments": '{"test": "value"}'}
result = _get_function_arguments(function)
assert result == {"test": "value"}
# Test with dict arguments
function = {"arguments": {"test": "value"}}
result = _get_function_arguments(function)
assert result == {"test": "value"}
# Test with invalid JSON string
function = {"arguments": "invalid json"}
result = _get_function_arguments(function)
assert result == {}
# Test with no arguments
function = {}
result = _get_function_arguments(function)
assert result == {}
@pytest.mark.asyncio()
async def test_call_openai_tool(mock_session, mock_mcp_tool_call_result):
mock_session.call_tool.return_value = mock_mcp_tool_call_result
openai_tool = {
"function": {"name": "test_tool", "arguments": json.dumps({"test": "value"})}
}
result = await call_openai_tool(mock_session, openai_tool)
print("result of call_openai_tool", result)
assert result.content[0].text == "test_output"
mock_session.call_tool.assert_called_once_with(
name="test_tool", arguments={"test": "value"}
)
@pytest.mark.asyncio()
async def test_call_mcp_tool(mock_session, mock_mcp_tool_call_result):
mock_session.call_tool.return_value = mock_mcp_tool_call_result
request_params = CallToolRequestParams(
name="test_tool", arguments={"test": "value"}
)
result = await call_mcp_tool(mock_session, request_params)
print("call_mcp_tool result", result)
assert result.content[0].text == "test_output"
mock_session.call_tool.assert_called_once_with(
name="test_tool", arguments={"test": "value"}
)
def test_normalize_mcp_input_schema():
"""Test MCP input schema normalization for OpenAI compatibility."""
# Test case 1: Empty/None schema should get default structure
assert _normalize_mcp_input_schema(None) == {
"type": "object",
"properties": {},
"additionalProperties": False,
}
assert _normalize_mcp_input_schema({}) == {
"type": "object",
"properties": {},
"additionalProperties": False,
}
# Test case 2: Schema with only type should get properties added
schema_with_type_only = {"type": "object"}
normalized = _normalize_mcp_input_schema(schema_with_type_only)
assert normalized == {
"type": "object",
"properties": {},
"additionalProperties": False,
}
# Test case 3: Schema missing type should get type added
schema_missing_type = {"properties": {"param": {"type": "string"}}}
normalized = _normalize_mcp_input_schema(schema_missing_type)
assert normalized == {
"type": "object",
"properties": {"param": {"type": "string"}},
"additionalProperties": False,
}
# Test case 4: Complete schema should be preserved with additionalProperties added
complete_schema = {
"type": "object",
"properties": {"param": {"type": "string"}},
"required": ["param"],
}
normalized = _normalize_mcp_input_schema(complete_schema)
assert normalized == {
"type": "object",
"properties": {"param": {"type": "string"}},
"required": ["param"],
"additionalProperties": False,
}
# Test case 5: Schema with existing additionalProperties should be preserved
schema_with_additional = {
"type": "object",
"properties": {"param": {"type": "string"}},
"additionalProperties": True,
}
normalized = _normalize_mcp_input_schema(schema_with_additional)
assert normalized["additionalProperties"] == True
def test_transform_mcp_tool_to_openai_responses_api_tool():
"""Test transformation to OpenAI Responses API tool format with schema normalization."""
# Test case 1: Tool with minimal schema (the problematic case from the error)
minimal_tool = MCPTool(
name="GitMCP-fetch_litellm_documentation",
description="Fetch entire documentation file from GitHub repository",
inputSchema={"type": "object"}, # This was causing the error
)
openai_tool = transform_mcp_tool_to_openai_responses_api_tool(minimal_tool)
assert openai_tool["name"] == "GitMCP-fetch_litellm_documentation"
assert openai_tool["type"] == "function"
assert openai_tool["strict"] == False
assert openai_tool["parameters"]["type"] == "object"
assert openai_tool["parameters"]["properties"] == {}
assert openai_tool["parameters"]["additionalProperties"] == False
# Test case 2: Tool with complete schema
complete_tool = MCPTool(
name="test_tool_complete",
description="A test tool with complete schema",
inputSchema={
"type": "object",
"properties": {"query": {"type": "string", "description": "Search query"}},
"required": ["query"],
},
)
openai_tool = transform_mcp_tool_to_openai_responses_api_tool(complete_tool)
assert openai_tool["parameters"]["type"] == "object"
assert "query" in openai_tool["parameters"]["properties"]
assert openai_tool["parameters"]["required"] == ["query"]
assert openai_tool["parameters"]["additionalProperties"] == False
def test_transform_mcp_tool_to_anthropic_tool():
"""
Regression test (LIT-4517): MCP tools must reach /v1/messages in Anthropic's
own tool shape.
Given: An MCP tool
When: It is transformed for the Anthropic Messages API
Then: It carries name/description/input_schema, the shape that endpoint
accepts, rather than an OpenAI function block
/v1/messages rejects an OpenAI-shaped tool outright ("Input tag 'function'
does not match any of the expected tags"), so reusing either OpenAI
transform here loses every MCP tool.
"""
tool = MCPTool(
name="read_wiki_structure",
description="Get a list of documentation topics",
inputSchema={
"type": "object",
"properties": {"repoName": {"type": "string"}},
"required": ["repoName"],
},
)
anthropic_tool = transform_mcp_tool_to_anthropic_tool(tool)
assert anthropic_tool["name"] == "read_wiki_structure"
assert anthropic_tool["description"] == "Get a list of documentation topics"
assert anthropic_tool["type"] == "custom"
assert anthropic_tool["input_schema"]["type"] == "object"
assert "repoName" in anthropic_tool["input_schema"]["properties"]
assert anthropic_tool["input_schema"]["required"] == ["repoName"]
assert "function" not in anthropic_tool, "Anthropic tools must not carry an OpenAI function block"
assert "parameters" not in anthropic_tool, "Anthropic names the schema input_schema, not parameters"
def test_transform_mcp_tool_to_anthropic_tool_normalizes_empty_schema():
"""A tool with no declared arguments must still present a valid object schema."""
anthropic_tool = transform_mcp_tool_to_anthropic_tool(
MCPTool(name="noargs", description=None, inputSchema={})
)
assert anthropic_tool["name"] == "noargs"
assert anthropic_tool["description"] == ""
assert anthropic_tool["input_schema"]["type"] == "object"
assert anthropic_tool["input_schema"]["properties"] == {}
def test_transform_mcp_tool_to_anthropic_tool_strips_keys_anthropic_rejects():
"""
Regression test (LIT-4517): an MCP schema with keys Anthropic does not accept
must be sanitized, so the same tool cannot succeed on /chat/completions and 400
on /v1/messages.
Given: An MCP tool whose inputSchema carries $schema, legacy definitions and oneOf
When: It is transformed for the Anthropic Messages API
Then: Only keys in AnthropicInputSchema survive, matching the chat path
The chat path runs the schema through the same sanitizer, so before this the two
routes diverged: a clean-schema server (deepwiki) worked on both, but a server
with a richer schema would be rejected only on messages.
"""
from litellm.types.llms.anthropic import AnthropicInputSchema
tool = MCPTool(
name="rich",
description="tool with a dirty schema",
inputSchema={
"type": "object",
"properties": {"q": {"type": "string"}},
"required": ["q"],
"$schema": "http://json-schema.org/draft-07/schema#",
"definitions": {"D": {"type": "string"}},
"oneOf": [{"required": ["q"]}],
},
)
anthropic_tool = transform_mcp_tool_to_anthropic_tool(tool)
schema_keys = set(anthropic_tool["input_schema"].keys())
assert schema_keys <= set(AnthropicInputSchema.__annotations__.keys()), (
f"schema must only carry keys Anthropic accepts, got {schema_keys}"
)
assert "$schema" not in schema_keys
assert "definitions" not in schema_keys
assert "oneOf" not in schema_keys
assert anthropic_tool["input_schema"]["properties"] == {"q": {"type": "string"}}
assert anthropic_tool["input_schema"]["required"] == ["q"]