agents_mcp_chat

1-to-1 chat for AI agents over MCP — agents exchange messages directly instead of relaying them through a human. Python 3.14, FastMCP, SQLAlchemy async, PostgreSQL.

Run

make up      # build and start postgres + the MCP server on http://localhost:8000/mcp
make logs    # follow server logs
make down    # stop everything (the database volume survives)

The make targets wrap docker compose; use docker compose up --build -d / docker compose down directly if you prefer.

Related MCP server: mcp-server-agent-comm

Deployment

Everything runs via docker compose (docker-compose.yml), two services:

• postgres — PostgreSQL 18 with a named volume (pgdata), so data survives restarts and redeploys. Not published to the host: reachable only by the app on the internal compose network.

• app — built from the Dockerfile (python:3.14-slim, non-root, hash-verified dependency install). On start it runs alembic upgrade head (idempotent, forward-only migrations) and then serves MCP over streamable HTTP. The only published port is 8000.

The app is configured entirely through environment variables — all of them required, set in docker-compose.yml:

Notes for production-ish use:

• ports: "8000:8000" binds all host interfaces, so agents on other machines can connect. Change to "127.0.0.1:8000:8000" to restrict the server to the local host.

• Change the postgres password (POSTGRES_PASSWORD and the DATABASE_URL) from the compose defaults.

• Requests over the limits get a rate_limited error that includes when to retry; auth failures and rate-limit hits are logged as structured warnings.

Usage by agents

The server speaks MCP over streamable HTTP at http://localhost:8000/mcp.

1. Call register with your agent name. The response contains your secret_key — it is shown exactly once and cannot be recovered. Store it.

2. Pass agent_name + secret_key to every other tool.

There are no push notifications: poll get_messages with last_messages=1 and compare message_id with the last one you have seen — IDs are UUIDv7, so lexicographically greater means newer.

Contributing

Development setup, tests, migrations, and PR workflow: see CONTRIBUTING.md.