Files
Eduard van Valkenburg 9c57680f00 Python: Add header_provider to Streamable HTTP MCP servers (#4849)
* Python: Add header_provider to MCPStreamableHTTPTool (#4808)

Add a header_provider callback parameter to MCPStreamableHTTPTool that
enables injecting dynamic per-request HTTP headers from runtime kwargs
(originating from FunctionInvocationContext.kwargs set in agent middleware).

The implementation uses contextvars and httpx event hooks to ensure headers
are task-local and safe for concurrent tool calls:

- header_provider receives the runtime kwargs dict and returns headers
- call_tool sets a ContextVar before delegating to MCPTool.call_tool
- An httpx request event hook reads from the ContextVar and injects headers

Example usage:
    mcp_tool = MCPStreamableHTTPTool(
        name="web-api",
        url="https://api.example.com/mcp",
        header_provider=lambda kwargs: {
            "X-Auth-Token": kwargs.get("auth_token", ""),
        },
    )

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address review feedback for #4808: Python: [Bug]: Unable to pass AgentContext to MCPStreamableHTTPTool

* Add test for header_provider via FunctionTool.invoke with FunctionInvocationContext

Addresses PR review comment: exercises the full pipeline from
FunctionInvocationContext.kwargs through FunctionTool.invoke to
MCPStreamableHTTPTool.call_tool and header_provider, rather than
testing call_tool in isolation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address review feedback for #4808: review comment fixes

* Fix streamable MCP transport defaults

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix Azure AI test client mocks

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix MCP runtime kwarg regressions

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Stabilize MCP tool runtime kwargs

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Use context kwargs in MCP wrappers

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* updated mcp samples

* fix link

---------

Co-authored-by: Copilot <copilot@github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-03-31 17:23:49 +00:00

61 lines
2.3 KiB
Python

# Copyright (c) Microsoft. All rights reserved.
import asyncio
import sys
from agent_framework import Agent, MCPStreamableHTTPTool
from agent_framework.openai import OpenAIChatClient
from dotenv import load_dotenv
# Load environment variables from .env file
load_dotenv()
"""
MCP API Key Authentication Example
This sample demonstrates the runtime ``header_provider`` pattern for
``MCPStreamableHTTPTool``. The MCP tool derives authentication headers from
``function_invocation_kwargs`` passed to ``Agent.run(...)`` so the API key stays
in runtime context instead of being baked into a shared ``httpx.AsyncClient``.
Replace the ``url`` parameter in the ``MCPStreamableHTTPTool`` with your authenticated server URL and
run the sample with your API key as a command-line argument:
python mcp_api_key_auth.py <your_api_key>
The ``header_provider`` here is just a simple lambda, but it can be a more complex function that retrieves and
formats headers as needed, allowing for flexible authentication schemes.
For more complex scenarios, you could implement token refresh logic or support multiple authentication methods
within the header provider function.
For more authentication examples including OAuth 2.0 flows, see:
- https://github.com/modelcontextprotocol/python-sdk/tree/main/examples/clients/simple-auth-client
- https://github.com/modelcontextprotocol/python-sdk/tree/main/examples/servers/simple-auth
"""
async def api_key_auth_example(api_key: str) -> None:
"""Run an agent against an MCP server using runtime-provided API key headers."""
async with Agent(
client=OpenAIChatClient(),
name="Agent",
instructions="You are a helpful assistant. Use your MCP tool when answering the user's question.",
tools=MCPStreamableHTTPTool(
name="MCP tool",
description="MCP tool description.",
url="<your authenticated server url>",
header_provider=lambda kwargs: {"Authorization": f"Bearer {kwargs['mcp_api_key']}"},
),
) as agent:
query = "Use your MCP tool to tell me what tools are available to you."
print(f"User: {query}")
result = await agent.run(
query,
function_invocation_kwargs={"mcp_api_key": api_key},
)
print(f"Agent: {result.text}")
if __name__ == "__main__":
asyncio.run(api_key_auth_example(sys.argv[1]))