import inspect import tempfile from collections.abc import AsyncGenerator from pathlib import Path from typing import Any import pytest from fastmcp.client.auth.bearer import BearerAuth from fastmcp.client.auth.oauth import OAuthClientProvider from fastmcp.client.client import Client from fastmcp.client.logging import LogMessage from fastmcp.client.transports import ( MCPConfigTransport, SSETransport, StdioTransport, StreamableHttpTransport, ) from fastmcp.mcp_config import ( CanonicalMCPConfig, CanonicalMCPServerTypes, MCPConfig, MCPServerTypes, RemoteMCPServer, StdioMCPServer, TransformingStdioMCPServer, ) from fastmcp.tools.tool import Tool as FastMCPTool def test_parse_single_stdio_config(): config = { "mcpServers": { "test_server": { "command": "echo", "args": ["hello"], } } } mcp_config = MCPConfig.from_dict(config) transport = mcp_config.mcpServers["test_server"].to_transport() assert isinstance(transport, StdioTransport) assert transport.command == "echo" assert transport.args == ["hello"] def test_parse_extra_keys(): config = { "mcpServers": { "test_server": { "command": "echo", "args": ["hello"], "leaf_extra": "leaf_extra", } }, "root_extra": "root_extra", } mcp_config = MCPConfig.from_dict(config) serialized_mcp_config = mcp_config.to_dict() assert serialized_mcp_config["root_extra"] == "root_extra" assert ( serialized_mcp_config["mcpServers"]["test_server"]["leaf_extra"] == "leaf_extra" ) def test_parse_mcpservers_at_root(): config = { "test_server": { "command": "echo", "args": ["hello"], } } mcp_config = MCPConfig.from_dict(config) serialized_mcp_config = mcp_config.model_dump() assert serialized_mcp_config["mcpServers"]["test_server"]["command"] == "echo" assert serialized_mcp_config["mcpServers"]["test_server"]["args"] == ["hello"] def test_parse_mcpservers_discriminator(): """Test that the MCPConfig discriminator produces StdioMCPServer for a non-transforming server and TransformingStdioMCPServer for a transforming server.""" config = { "test_server": { "command": "echo", "args": ["hello"], }, "test_server_two": {"command": "echo", "args": ["hello"], "tools": {}}, } mcp_config = MCPConfig.from_dict(config) test_server: MCPServerTypes = mcp_config.mcpServers["test_server"] assert isinstance(test_server, StdioMCPServer) test_server_two: MCPServerTypes = mcp_config.mcpServers["test_server_two"] assert isinstance(test_server_two, TransformingStdioMCPServer) canonical_mcp_config = CanonicalMCPConfig.from_dict(config) canonical_test_server: CanonicalMCPServerTypes = canonical_mcp_config.mcpServers[ "test_server" ] assert isinstance(canonical_test_server, StdioMCPServer) canonical_test_server_two: CanonicalMCPServerTypes = ( canonical_mcp_config.mcpServers["test_server_two"] ) assert isinstance(canonical_test_server_two, StdioMCPServer) def test_parse_single_remote_config(): config = { "mcpServers": { "test_server": { "url": "http://localhost:8000", } } } mcp_config = MCPConfig.from_dict(config) transport = mcp_config.mcpServers["test_server"].to_transport() assert isinstance(transport, StreamableHttpTransport) assert transport.url == "http://localhost:8000" def test_parse_remote_config_with_transport(): config = { "mcpServers": { "test_server": { "url": "http://localhost:8000", "transport": "sse", } } } mcp_config = MCPConfig.from_dict(config) transport = mcp_config.mcpServers["test_server"].to_transport() assert isinstance(transport, SSETransport) assert transport.url == "http://localhost:8000" def test_parse_remote_config_with_url_inference(): config = { "mcpServers": { "test_server": { "url": "http://localhost:8000/sse/", } } } mcp_config = MCPConfig.from_dict(config) transport = mcp_config.mcpServers["test_server"].to_transport() assert isinstance(transport, SSETransport) assert transport.url == "http://localhost:8000/sse/" def test_parse_multiple_servers(): config = { "mcpServers": { "test_server": { "url": "http://localhost:8000/sse/", }, "test_server_2": { "command": "echo", "args": ["hello"], "env": {"TEST": "test"}, }, } } mcp_config = MCPConfig.from_dict(config) assert len(mcp_config.mcpServers) == 2 assert isinstance(mcp_config.mcpServers["test_server"], RemoteMCPServer) assert isinstance(mcp_config.mcpServers["test_server"].to_transport(), SSETransport) assert isinstance(mcp_config.mcpServers["test_server_2"], StdioMCPServer) assert isinstance( mcp_config.mcpServers["test_server_2"].to_transport(), StdioTransport ) assert mcp_config.mcpServers["test_server_2"].command == "echo" assert mcp_config.mcpServers["test_server_2"].args == ["hello"] assert mcp_config.mcpServers["test_server_2"].env == {"TEST": "test"} async def test_multi_client(tmp_path: Path): server_script = inspect.cleandoc(""" from fastmcp import FastMCP mcp = FastMCP() @mcp.tool def add(a: int, b: int) -> int: return a + b if __name__ == '__main__': mcp.run() """) script_path = tmp_path / "test.py" script_path.write_text(server_script) config = { "mcpServers": { "test_1": { "command": "python", "args": [str(script_path)], }, "test_2": { "command": "python", "args": [str(script_path)], }, } } client = Client(config) async with client: tools = await client.list_tools() assert len(tools) == 2 result_1 = await client.call_tool("test_1_add", {"a": 1, "b": 2}) result_2 = await client.call_tool("test_2_add", {"a": 1, "b": 2}) assert result_1.data == 3 assert result_2.data == 3 async def test_remote_config_default_no_auth(): config = { "mcpServers": { "test_server": { "url": "http://localhost:8000", } } } client = Client(config) assert isinstance(client.transport.transport, StreamableHttpTransport) assert client.transport.transport.auth is None async def test_remote_config_with_auth_token(): config = { "mcpServers": { "test_server": { "url": "http://localhost:8000", "auth": "test_token", } } } client = Client(config) assert isinstance(client.transport.transport, StreamableHttpTransport) assert isinstance(client.transport.transport.auth, BearerAuth) assert client.transport.transport.auth.token.get_secret_value() == "test_token" async def test_remote_config_sse_with_auth_token(): config = { "mcpServers": { "test_server": { "url": "http://localhost:8000/sse/", "auth": "test_token", } } } client = Client(config) assert isinstance(client.transport.transport, SSETransport) assert isinstance(client.transport.transport.auth, BearerAuth) assert client.transport.transport.auth.token.get_secret_value() == "test_token" async def test_remote_config_with_oauth_literal(): config = { "mcpServers": { "test_server": { "url": "http://localhost:8000", "auth": "oauth", } } } client = Client(config) assert isinstance(client.transport.transport, StreamableHttpTransport) assert isinstance(client.transport.transport.auth, OAuthClientProvider) async def test_multi_client_with_logging(tmp_path: Path): """ Tests that logging is properly forwarded to the ultimate client. """ server_script = inspect.cleandoc(""" from fastmcp import FastMCP, Context mcp = FastMCP() @mcp.tool async def log_test(message: str, ctx: Context) -> int: await ctx.log(message) return 42 if __name__ == '__main__': mcp.run() """) script_path = tmp_path / "test.py" script_path.write_text(server_script) config = { "mcpServers": { "test_server": { "command": "python", "args": [str(script_path)], }, "test_server_2": { "command": "python", "args": [str(script_path)], }, } } MESSAGES = [] async def log_handler(message: LogMessage): MESSAGES.append(message) async with Client(config, log_handler=log_handler) as client: result = await client.call_tool("test_server_log_test", {"message": "test 42"}) assert result.data == 42 assert len(MESSAGES) == 1 assert MESSAGES[0].data == "test 42" async def test_multi_client_with_transforms(tmp_path: Path): """ Tests that transforms are properly applied to the tools. """ server_script = inspect.cleandoc(""" from fastmcp import FastMCP mcp = FastMCP() @mcp.tool def add(a: int, b: int) -> int: return a + b if __name__ == '__main__': mcp.run() """) script_path = tmp_path / "test.py" script_path.write_text(server_script) config = { "mcpServers": { "test_1": { "command": "python", "args": [str(script_path)], "tools": { "add": { "name": "transformed_add", "arguments": { "a": {"name": "transformed_a"}, "b": {"name": "transformed_b"}, }, } }, }, "test_2": { "command": "python", "args": [str(script_path)], }, } } client = Client[MCPConfigTransport](config) async with client: tools = await client.list_tools() tools_by_name = {tool.name: tool for tool in tools} assert len(tools) == 2 assert "test_1_transformed_add" in tools_by_name result = await client.call_tool( "test_1_transformed_add", {"transformed_a": 1, "transformed_b": 2} ) assert result.data == 3 async def test_canonical_multi_client_with_transforms(tmp_path: Path): """Test that transforms are not applied to servers in a canonical MCPConfig.""" server_script = inspect.cleandoc(""" from fastmcp import FastMCP mcp = FastMCP() @mcp.tool def add(a: int, b: int) -> int: return a + b if __name__ == '__main__': mcp.run() """) script_path = tmp_path / "test.py" script_path.write_text(server_script) config = CanonicalMCPConfig( mcpServers={ "test_1": { "command": "python", "args": [str(script_path)], "tools": { # <--- Will be ignored as its not valid for a canonical MCPConfig "add": { "name": "transformed_add", "arguments": { "a": {"name": "transformed_a"}, "b": {"name": "transformed_b"}, }, } }, }, "test_2": { "command": "python", "args": [str(script_path)], }, } # type: ignore[reportUnknownArgumentType] ) client = Client(config) async with client: tools = await client.list_tools() tools_by_name = {tool.name: tool for tool in tools} assert len(tools) == 2 assert "test_1_transformed_add" not in tools_by_name async def test_multi_client_transform_with_filtering(tmp_path: Path): """ Tests that tag-based filtering works when using a transforming MCPConfig. """ server_script = inspect.cleandoc(""" from fastmcp import FastMCP mcp = FastMCP() @mcp.tool def add(a: int, b: int) -> int: return a + b @mcp.tool def subtract(a: int, b: int) -> int: return a - b if __name__ == '__main__': mcp.run() """) script_path = tmp_path / "test.py" script_path.write_text(server_script) config = { "mcpServers": { "test_1": { "command": "python", "args": [str(script_path)], "tools": { "add": { "name": "transformed_add", "tags": ["keep"], "arguments": { "a": {"name": "transformed_a"}, "b": {"name": "transformed_b"}, }, }, }, "include_tags": ["keep"], }, "test_2": { "command": "python", "args": [str(script_path)], }, } } client = Client[MCPConfigTransport](config) async with client: tools = await client.list_tools() tools_by_name = {tool.name: tool for tool in tools} assert len(tools) == 3 assert "test_1_transformed_add" in tools_by_name assert "test_1_add" not in tools_by_name assert "test_1_subtract" not in tools_by_name assert "test_2_add" in tools_by_name assert "test_2_subtract" in tools_by_name async def test_multi_client_with_elicitation(tmp_path: Path): """ Tests that elicitation is properly forwarded to the ultimate client. """ server_script = inspect.cleandoc(""" from fastmcp import FastMCP, Context mcp = FastMCP() @mcp.tool async def elicit_test(ctx: Context) -> int: result = await ctx.elicit('Pick a number', response_type=int) return result.data if __name__ == '__main__': mcp.run() """) script_path = tmp_path / "test.py" script_path.write_text(server_script) config = { "mcpServers": { "test_server": { "command": "python", "args": [str(script_path)], }, "test_server_2": { "command": "python", "args": [str(script_path)], }, } } async def elicitation_handler(message, response_type, params, ctx): return response_type(value=42) async with Client(config, elicitation_handler=elicitation_handler) as client: result = await client.call_tool("test_server_elicit_test", {}) assert result.data == 42 def sample_tool_fn(arg1: int, arg2: str) -> str: return f"Hello, world! {arg1} {arg2}" @pytest.fixture def sample_tool() -> FastMCPTool: return FastMCPTool.from_function(sample_tool_fn, name="sample_tool") @pytest.fixture async def test_script(tmp_path: Path) -> AsyncGenerator[Path, Any]: with tempfile.NamedTemporaryFile() as f: f.write(b""" from fastmcp import FastMCP mcp = FastMCP() @mcp.tool def fetch(url: str) -> str: return f"Hello, world! {url}" if __name__ == '__main__': mcp.run() """) yield Path(f.name) pass