MCP Gateway

MCP Gateway

MCP (Model Context Protocol) Gateway can translate MCP tool callings to traditional HTTP API requests. It can provide a configurable way to get existing HTTP API to MCP territory.

Getting Started

Create config file from config.example.yaml:

$ cp config.example.yaml config.yaml

Edit config.yaml file, map all APIs to MCP tools.

Then start launch it with SSE transport:

$ uv run mcp-gateway
INFO:     Started server process [15400]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://0.0.0.0:3001 (Press CTRL+C to quit)

Default is 3001.

Server Control

Change Port

Provide parameter --port=<port_no> in command line will change the port to SSE transport.

Launch gateway with port 3002:

$ uv run mcp-gateway --port=3002
INFO:     Started server process [15400]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://0.0.0.0:3002 (Press CTRL+C to quit)

stdio Transport

Provide parameter --transport=stdio in command line will change the transport to stdio.

E.G.:

$ uv run mcp-gateway --transport=stdio

It's meaningless to manually launch gateway in stdio transport. You can configure in Cursor or Cline like:

{
    "mcpServers": {
        "mcp-gateway": {
          "command": "uv",
          "args": ["run", "mcp-gateway", "--transport=stdio"]
        }
      }
}

Or MCP Inspector with form values:

| Item | Value | | -------------- | --------------------------------- | | Transport Type | STDIO | | Command | uv | | Arguments | run mcp-gateway --transport=stdio |

Configuration File

There is two parts in configuration YAML, server and tools. server defines the basic info for gateway server use. tools defines the mapping from single MCP tool to HTTP API request.

server:
  name: rest-amap-server
  config:
    apiKey: foo
tools:
- name: maps-geo
  description: "将详细的结构化地址转换为经纬度坐标。支持对地标性名胜景区、建筑物名称解析为经纬度坐标"
  args:
  - name: address
    description: "待解析的结构化地址信息"
    required: true
  - name: city
    description: "指定查询的城市"
    required: false
  requestTemplate:
    url: "https://restapi.amap.com/v3/geocode/geo?key={{.config.apiKey}}&address={{.args.address}}&city={{.args.city}}&source=ts_mcp"
    method: GET
    headers:
    - key: x-api-key
      value: "{{.config.apiKey}}"
    - key: Content-Type
      value: application/json
  responseTemplate:
    body: |
      # 地理编码信息
      {{- range $index, $geo := .Geocodes }}
      ## 地点 {{add $index 1}}

      - **国家**: {{ $geo.Country }}
      - **省份**: {{ $geo.Province }}
      - **城市**: {{ $geo.City }}
      - **城市代码**: {{ $geo.Citycode }}
      - **区/县**: {{ $geo.District }}
      - **街道**: {{ $geo.Street }}
      - **门牌号**: {{ $geo.Number }}
      - **行政编码**: {{ $geo.Adcode }}
      - **坐标**: {{ $geo.Location }}
      - **级别**: {{ $geo.Level }}
      {{- end }}

Server

| Item | Description | | ------ | ------------------------------------------------------------ | | name | Server name | | config | Key/Value pairs that can be referenced by var {{.config.xxx}} in templates |

Tools

tools is list of MCP tools mapping. Single tool props. are defined as follows:

| Item | Description | | ---------------- | ------------------------------------------------------------ | | name | Tool name (Function name), which is provided to LLM. | | description | Tool description through which LLM can understand what the tool could do. | | args | Arguments of tool (Function arguments). | | requestTemplate | Request mapping to target HTTP API. | | responseTemplate | Response mapping for response of target HTTP API. |

Single argument props. are defined as follows:

| Item | Type | Description | | ----------- | ------- | ------------------------------------------------------------ | | name | | Argument name, which is provided to LLM. | | description | | Argument description through which LLM can understand and decide what value should be filled. | | required | Boolean | Required argument or not. |

Request template props. are defined as follows:

| Item | Description | | ------- | ---------------------------- | | method | HTTP method | | url | Target HTTP API url template | | headers | HTTP headers |

HTTP headers are defined as follows:

| Item | Description | | ----- | --------------------- | | key | Header key | | value | Header value template |

Response template props are defined as follows:

| Item | Description | | ---- | ---------------------- | | body | Response body template |

Contribution

All kinds of contribution are welcomed.