# fastapi-mcp-server ⚡

> Turn any FastAPI app into a Claude-compatible MCP server instantly by reading its OpenAPI spec

## What it does

Point this tool at any running FastAPI app and it will:
1. Fetch the OpenAPI spec automatically from `/openapi.json`
2. Parse every endpoint — paths, methods, parameters, request bodies
3. Dynamically register one MCP tool per endpoint
4. Claude can now call any endpoint using natural language

**Zero manual tool writing. Zero code changes to your existing FastAPI app.**

## Demo

```
User: "Create a task titled Push code to GitHub with high priority"
Claude: [calls post_tasks tool]
        → Task created successfully ✅

User: "Mark task 2 as completed"
Claude: [calls put_tasks_task_id tool]
        → Task updated ✅

User: "Show me all tasks"
Claude: [calls get_tasks tool]
        → Returns all tasks ✅
```

## Architecture

```
Your FastAPI App (running)
        ↓
fastapi-mcp-server fetches /openapi.json
        ↓
OpenAPIParser extracts all endpoints
        ↓
One MCP tool registered per endpoint
        ↓
Claude calls tools using natural language
        ↓
MCP server makes real HTTP requests to your API
        ↓
Results returned to Claude
```

## Tech Stack

- Python 3.12
- FastAPI + Pydantic
- MCP (Model Context Protocol)
- httpx
- OpenAPI 3.x

## Setup

### 1. Clone and install
```bash
git clone https://github.com/vkmech999/fastapi-mcp-server.git
cd fastapi-mcp-server
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt
```

### 2. Configure environment
```bash
cp .env.example .env
# Set TARGET_API_URL to your FastAPI app
# Set AUTH_TYPE if your API requires authentication
```

### 3. Connect to Claude Desktop

Add to `~/Library/Application Support/Claude/claude_desktop_config.json`:

```json
{
  "mcpServers": {
    "fastapi-mcp-server": {
      "command": "/path/to/venv/bin/python3",
      "args": ["-m", "mcp_server.server"],
      "env": {
        "TARGET_API_URL": "http://localhost:8000",
        "AUTH_TYPE": "none",
        "PYTHONPATH": "/path/to/fastapi-mcp-server"
      }
    }
  }
}
```

### 4. Use it in Claude Desktop

```
"List all available endpoints"
"Get all tasks"
"Create a new user named John with email john@example.com"
"Delete task with ID 3"
```

## Authentication Support

| Auth Type | Use Case | Config |
|-----------|----------|--------|
| `none` | Public APIs | `AUTH_TYPE=none` |
| `bearer` | JWT / OAuth2 | `AUTH_TYPE=bearer` + `AUTH_TOKEN=eyJ...` |
| `api_key` | Third-party APIs | `AUTH_TYPE=api_key` + `AUTH_TOKEN=sk-...` + `AUTH_HEADER=X-API-Key` |
| `basic` | Legacy systems | `AUTH_TYPE=basic` + `AUTH_USERNAME` + `AUTH_PASSWORD` |

## MCP Tools

| Tool | Description |
|------|-------------|
| `list_api_endpoints` | Discover all registered endpoint tools |
| `get_*` | Auto-generated GET endpoint tools |
| `post_*` | Auto-generated POST endpoint tools |
| `put_*` | Auto-generated PUT endpoint tools |
| `delete_*` | Auto-generated DELETE endpoint tools |

## Running Tests

```bash
pytest tests/test_server.py -v
```

## Author

**Vivek Kumar** — Senior Python Full Stack Developer  
[LinkedIn](https://linkedin.com/in/vivek-kumar-80943a104) · [GitHub](https://github.com/vkmech999)