FastAPI MCP-Style Server

Minimal FastAPI implementation that mimics a subset of Model Context Protocol (MCP) functionality.

Features

• Echo-style POST /mcp endpoint returning structured response (id, status, outputs)
• JSON-RPC 2.0 endpoint /mcp/rpc supporting:
  • mcp.list_tools
  • mcp.call_tool (tools: echo, uppercase, query_manse, calc_daewoon)
• GET usage helper /mcp
• Pydantic models for request/response
• Basic logging
• Tests (pytest) for REST + RPC

Quick Start

python -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt
uvicorn main:app --reload

REST Usage

curl -X POST http://127.0.0.1:8000/mcp \
  -H 'Content-Type: application/json' \
  -d '{"inputs": {"text": "hello"}}'

JSON-RPC Examples

List tools:

curl -X POST http://127.0.0.1:8000/mcp/rpc \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"mcp.list_tools"}'

Call echo:

curl -X POST http://127.0.0.1:8000/mcp/rpc \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":"abc","method":"mcp.call_tool","params":{"name":"echo","arguments":{"text":"hello"}}}'

Call query_manse (first 5 rows):

curl -X POST http://127.0.0.1:8000/mcp/rpc \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":2,"method":"mcp.call_tool","params":{"name":"query_manse","arguments":{"limit":5}}}'

Call calc_daewoon (example date):

curl -X POST http://127.0.0.1:8000/mcp/rpc \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":3,"method":"mcp.call_tool","params":{"name":"calc_daewoon","arguments":{"yyyymmdd":"20250115"}}}'

Response example:

{
  "jsonrpc": "2.0",
  "id": 3,
  "result": {
    "outputs": [
      {"type": "json", "content": {"asc_diff_days": 3, "desc_diff_days": 2}}
    ]
  }
}

Meaning:

• asc_diff_days: 기준일 이후 다음 절기까지 (일수 / 3 반올림)
• desc_diff_days: 기준일 이전 직전 절기까지 (일수 / 3 반올림)
• 없으면 null

Environment Variables (DB)

Variable	Default	Description
MCP_DB_HOST	192.168.31.136	MariaDB host
MCP_DB_PORT	3306	MariaDB port
MCP_DB_USER		DB user
MCP_DB_PASSWORD		DB password
MCP_DB_NAME	manse	Database name

Example run with overrides:

MCP_DB_HOST=127.0.0.1 MCP_DB_USER=app MCP_DB_PASSWORD=secret uvicorn main:app --reload

Run Tests

pytest -q

Next Ideas

• Streaming (SSE) outputs
• Prompts/resources primitives
• Auth layer (OAuth / API key)
• Tool change events