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.