# FastAPI MCP Server (Single Tool)
A minimal, production-ready **MCP server** implemented with **FastAPI** and deployable to **Google Cloud Run**. It exposes a single tool `get_time` via the OpenAI **Model Context Protocol (MCP)** using JSON‑RPC 2.0 over HTTP.
## Features
- `tools/list` and `tools/call` implemented exactly to spec
- Returns **content** (text for humans) and **structuredContent** (JSON for machines)
- Proper JSON‑RPC error codes and input validation with `jsonschema`
- CORS enabled (dev) + optional API key auth via `x-api-key`
- Health check (`/healthz`) and simple request logging
- Dockerfile and one‑command Cloud Run deploy
## Endpoints
- `POST /` — JSON‑RPC 2.0 endpoint for `tools/list` and `tools/call`
- `GET /healthz` — returns `{ "ok": true }`
## Tool
### `get_time`
**Description:** Returns the current UTC timestamp, optionally formatted.
**Input schema:**
```json
{
"type": "object",
"properties": {
"format": {
"type": "string",
"description": "strftime format, e.g. %Y-%m-%dT%H:%M:%SZ"
}
},
"required": []
}
```
**Output structuredContent:**
```json
{
"iso": "2025-01-01T00:00:00Z",
"formatted": "optional if format passed"
}
```
## Local Dev
```bash
python -m venv .venv && source .venv/bin/activate
pip install -r requirements.txt
uvicorn app:app --reload --port 8000
```
Test:
```bash
curl -s localhost:8000/ -H 'content-type: application/json' -d '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}' | jq
curl -s localhost:8000/ -H 'content-type: application/json' -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"get_time","arguments":{"format":"%Y-%m-%dT%H:%M:%SZ"}}}' | jq
```
If you set `API_KEY=secret`, include a header: `-H 'x-api-key: secret'`
## Deploy to Google Cloud Run
Option 1 — from source (simplest):
```bash
./deploy.sh
# Set PROJECT_ID, REGION, SERVICE (or export them)
```
Option 2 — via Cloud Build pipeline:
```bash
gcloud builds submit --project $PROJECT_ID --substitutions=_REGION=us-central1,_SERVICE=mcp-clock
```
## Wire into OpenAI Agent Builder
- Add a new **MCP Server** to your agent
- **Server URL**: your Cloud Run URL (e.g. `https://mcp-clock-xxxx-uc.a.run.app`)
- **Label**: `clock`
- **Allowed tools**: `get_time` (or leave empty to allow all)
## License
MIT
