grok-faf-mcp

Instructions

Implementation Reference

• src/handlers/fileHandler.ts:163-229 (handler)

  The handleFafWrite function implements the logic for the faf_write tool, including path validation, size checking, directory creation, and writing the file.

  export async function handleFafWrite(args: any): Promise<CallToolResult> {
    const startTime = Date.now();
    
    try {
      const { path: filePath, content } = args;
      
      // Validate path
      const pathValidation = PathValidator.validate(filePath);
      if (!pathValidation.valid) {
        return {
          content: [{
            type: 'text',
            text: `❌ Security error: ${pathValidation.error}`
          }],
          isError: true
        };
      }
      
      // Check content size
      const contentSize = Buffer.byteLength(content, 'utf8');
      if (contentSize > 50 * 1024 * 1024) {
        return {
          content: [{
            type: 'text',
            text: `❌ Content too large: ${(contentSize / 1024 / 1024).toFixed(2)}MB (max: 50MB)`
          }],
          isError: true
        };
      }
      
      // Create directory if needed
      const dir = path.dirname(filePath);
      await fs.mkdir(dir, { recursive: true });
      
      // Write file with timeout
      await Promise.race([
        fs.writeFile(filePath, content, 'utf8'),
        new Promise<never>((_, reject) => 
          setTimeout(() => reject(new Error('Write timeout (30s)')), 30000)
        )
      ]);
      
      const duration = Date.now() - startTime;
      
      return {
        content: [{
          type: 'text',
          text: `✅ Successfully wrote ${contentSize} bytes to ${path.resolve(filePath)}`
        }],
        metadata: {
          duration_ms: duration,
          bytes_written: contentSize,
          file_path: path.resolve(filePath),
          message: `✅ Write completed in ${duration}ms`
        }
      };
      
    } catch (error: any) {
      return {
        content: [{
          type: 'text',
          text: `❌ Failed to write file: ${error.message}`
        }],
        isError: true
      };
    }
  }

• src/handlers/fileHandler.ts:73-90 (schema)

  The fafWriteTool object defines the MCP tool schema for 'faf_write', specifying the input requirements.

  export const fafWriteTool: Tool = {
    name: 'faf_write',
    description: 'Write content to any file on the local filesystem',
    inputSchema: {
      type: 'object',
      properties: {
        path: {
          type: 'string',
          description: 'Absolute or relative file path to write'
        },
        content: {
          type: 'string',
          description: 'Content to write to the file'
        }
      },
      required: ['path', 'content']
    }
  };