imcp-addon

The SDK for one containerised MCP capability: an addon declares tools, serves pages, knows who is calling, and keeps its own SQLite storage. Install the server extra for uvicorn, which run() needs:

pip install imcp-addon[serve]

A minimal addon — server.py

from imcp_addon import Addon, Request, ToolRequest, html

app = Addon(name="notes", title="Notes", schema=["CREATE TABLE note (account TEXT, text TEXT)"])


@app.tool("note_add", "Save a note for the current caller.")
async def note_add(request: ToolRequest, text: str) -> dict[str, str]:
    request.store.insert("note", {"account": request.identity.account or "", "text": text})
    return {"saved": text}


@app.page("/", title="Notes")
async def notes_page(request: Request) -> str:
    notes = request.store.fetch_all("SELECT text FROM note")
    body = html.card(None, *[html.el("p", text=row["text"]) for row in notes])
    return html.page("Notes", body, base=request.base).render()


app.run()

Set IMCP_ADDON_DATA to a data directory and PORT to a free port, then python server.py. That path is for local work only: in production the gateway starts the container, passes the caller's signed identity in headers and proxies the pages and /mcp, so an addon implements no routing, authentication or billing of its own.

The contract, storage rules and the page kit are in docs/ADDONS.md.