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MCP extension notes

This sample exposes the live repo data fetcher as an Azure Functions MCP extension tool and can consume that same Functions-hosted MCP service from the Copilot SDK.

The full Azure Functions tutorial belongs in Microsoft Learn. Start with Tutorial: Host an MCP server on Azure Functions, then use these sample-specific notes to see how the pieces map into this repo.

Expose a Functions MCP tool

The repo digest data fetcher is exposed from function_app.py with the Python v2 Functions programming model:

@app.mcp_tool()
@app.mcp_tool_property(
    arg_name="repository",
    description="Public GitHub repository in owner/name format.",
    is_required=False,
)
def get_repo_digest_context(repository: str = DEFAULT_REPOSITORY) -> str:
    return json.dumps(_repo_digest_context(repository), indent=2)

The Functions MCP extension exposes the server at:

http://localhost:7071/runtime/webhooks/mcp

For a deployed Function App, use:

https://<app-name>.azurewebsites.net/runtime/webhooks/mcp

Remote endpoints require the mcp_extension system key unless host.json is configured for anonymous webhook authorization. Get the deployed key with:

az functionapp keys list \
  --resource-group <resource-group> \
  --name <function-app-name> \
  --query systemKeys.mcp_extension \
  --output tsv

Consume the Functions MCP service from Copilot SDK

Pass the Functions MCP endpoint as a remote HTTP MCP server when creating a Copilot SDK session:

session = await client.create_session(
    on_permission_request=PermissionHandler.approve_all,
    mcp_servers={
        "repo-digest-functions": {
            "type": "http",
            "url": "https://<app-name>.azurewebsites.net/runtime/webhooks/mcp",
            "headers": {"x-functions-key": "<mcp_extension system key>"},
            "tools": ["get_repo_digest_context"],
        }
    },
)

For local loopback in this sample, set:

export COPILOT_MCP_SERVER_URL="http://localhost:7071/runtime/webhooks/mcp"

For a deployed Function App endpoint, also set:

export MCP_EXTENSION_KEY="<mcp_extension system key>"

When COPILOT_MCP_SERVER_URL is set, function_app.py passes the MCP server into CopilotClient.create_session and asks the model to call get_repo_digest_context for live GitHub data. If COPILOT_MCP_SERVER_URL is not set, the sample falls back to fetching public GitHub REST data directly before sending the prompt to the model.

References