Fetch API MCP Server

Implementation Reference

• src/handler.js:5-80 (handler)

  The fetchApiHandler function implements the core logic of the 'request' tool, handling HTTP requests with support for methods, headers, formData, jsonData, cookies, response parsing (JSON/text/binary as base64), and error handling.

  export async function fetchApiHandler({ url, method, headers = {}, formData, jsonData, cookies }) {
    try {
      // 准备请求选项
      const options = {
        method,
        headers: { ...headers },
      };
  
      // 处理cookies
      if (cookies && Object.keys(cookies).length > 0) {
        const cookieString = Object.entries(cookies)
          .map(([key, value]) => `${key}=${value}`)
          .join('; ');
        options.headers.Cookie = cookieString;
      }
  
      // 处理请求体
      if (method !== 'GET' && method !== 'HEAD') {
        if (formData && Object.keys(formData).length > 0) {
          // 处理表单数据
          const form = new URLSearchParams();
          Object.entries(formData).forEach(([key, value]) => {
            form.append(key, value);
          });
          options.body = form.toString();
          options.headers['Content-Type'] = 'application/x-www-form-urlencoded';
        } else if (jsonData) {
          // 处理JSON数据
          options.body = JSON.stringify(jsonData);
          options.headers['Content-Type'] = 'application/json';
        }
      }
  
      // 发送请求
      const response = await fetch(url, options);
      
      // 获取响应头
      const responseHeaders = {};
      response.headers.forEach((value, key) => {
        responseHeaders[key] = value;
      });
  
      // 尝试解析响应体
      let data;
      const contentType = response.headers.get('content-type');
      
      if (contentType?.includes('application/json')) {
        data = await response.json();
      } else if (contentType?.includes('text/')) {
        data = await response.text();
      } else {
        // 对于二进制数据，转换为base64字符串
        const buffer = await response.arrayBuffer();
        data = Buffer.from(buffer).toString('base64');
      }
  
      // 返回结果
      return {
        status: response.status,
        statusText: response.statusText,
        headers: responseHeaders,
        data,
      };
    } catch (error) {
      // 处理错误
      return {
        status: 500,
        statusText: 'Internal Server Error',
        headers: {},
        data: {
          error: error.message,
          stack: error.stack,
        },
      };
    }
  } 

• src/index.js:15-22 (schema)

  Zod input schema defining validation for 'request' tool parameters: url (required), method (default GET), optional headers, formData, jsonData, cookies.

  const inputSchema = {
    url: z.string().url(),
    method: z.enum(['GET', 'POST', 'PUT', 'DELETE', 'PATCH', 'HEAD', 'OPTIONS']).default('GET'),
    headers: z.record(z.string()).optional(),
    formData: z.record(z.string()).optional(),
    jsonData: z.any().optional(),
    cookies: z.record(z.string()).optional(),
  };

• src/index.js:25-37 (registration)

  MCP server.tool registration for 'request' tool, providing schema, a thin wrapper handler calling fetchApiHandler and formatting MCP response, and a detailed description.

  server.tool(
    'request',
    inputSchema,
    async (params) => {
      const result = await fetchApiHandler(params);
      return {
        content: [{ type: "text", text: JSON.stringify(result, null, 2) }]
      };
    },
    {
      description: '发送API请求并返回结果。使用方法：传入url（必需）、method（可选，默认GET）、headers（可选）、formData（可选，用于表单数据）、jsonData（可选，用于JSON数据）和cookies（可选）参数。例如：{ "url": "https://example.com/api", "method": "POST", "headers": {"Content-Type": "application/json"}, "jsonData": {"key": "value"}, "cookies": {"key": "value"} }。GET请求示例：{ "url": "https://example.com/api" }。返回包含status、statusText、headers和data的响应对象。'
    }
  );