Add an MCP server¶

Agent Plugins 1.0 supports skill-only, MCP-only, and mixed packages. This chapter adds a Python-standard-library-only MCP server to the release-notes plugin and verifies its handshake before VS Code starts it.

Begin after the first skill pull request is merged. Switch to a clean, current main, then create a plugin-wide branch:

git switch main
git pull --ff-only
uv run forge plugin-branch --plugin release-notes --topic add-status-mcp

Skill branches stay limited to one skill. A plugin/<plugin>/<topic> branch allows MCP and other plugin-wide files without allowing changes to another plugin.

Add the runtime and portable configuration¶

Copy the tested tutorial files:

cp examples/tutorial/status-mcp/server.py plugins/release-notes/server.py
cp examples/tutorial/status-mcp/mcp.json plugins/release-notes/mcp.json

Open plugins/release-notes/plugin.json and change its version from 0.1.0 to 0.2.0.

The portable mcp.json uses the cross-platform uv launcher and passes each argument separately. It omits cwd, so the Agent Plugins default is the plugin root. It does not contain a shell command, credentials, or a path outside the plugin.

Test the server process directly¶

Run one MCP initialize request without involving an AI model:

printf '%s\n' \
  '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"forge-tutorial","version":"1.0.0"}}}' \
  '{"jsonrpc":"2.0","method":"notifications/initialized"}' \
  | PLUGIN_ROOT="$PWD/plugins/release-notes" PLUGIN_DATA="$PWD/.tmp-plugin-data" \
    uv run --no-project python plugins/release-notes/server.py

The one-line JSON response should contain "name":"release-status" and "version":"1.0.0".

Generate both client marketplaces¶

Run:

uv run forge generate
uv run forge check
uv run pytest --no-cov tests/test_mcp.py tests/test_tutorial_mcp_server.py

The portable package keeps mcp.json and server.py unchanged. Both client marketplaces point to that same package, and Forge validates the portable MCP contract once.

Check it in VS Code¶

Run Developer: Reload Window, then open Chat: Open Customizations > Plugins. The release-notes plugin should still be enabled. Its release-status server should also appear in the MCP server list.

In Copilot Chat, ask:

Call release_status and report the result exactly.

The tool returns status: ready and confirms that VS Code supplied PLUGIN_ROOT and PLUGIN_DATA.

Recap¶

You added a real MCP process, tested the complete wire handshake without AI credentials, regenerated both marketplaces, and loaded the portable configuration in VS Code.