Tree-Hugger-JS MCP Server

Instructions

Implementation Reference

• src/index.ts:455-516 (handler)

  The main execution logic for the parse_code tool. Parses JavaScript/TypeScript code from a file path or string using tree-hugger-js, detects language, handles errors, stores the AST in state, and returns parsing summary.

  private async parseCode(args: { source: string; isFilePath?: boolean; language?: string }) {
    try {
      let sourceCode: string;
      let filePath: string | undefined;
      let isFile: boolean = args.isFilePath ?? false;
  
      // Auto-detect if it's a file path
      if (args.isFilePath === undefined) {
        isFile = !args.source.includes('\n') && !args.source.includes(';') && args.source.length < 200;
      }
  
      let tree: TreeHugger;
      
      if (isFile) {
        const resolvedPath = resolve(args.source);
        if (!existsSync(resolvedPath)) {
          return {
            content: [{
              type: "text", 
              text: `File not found: ${resolvedPath}`,
            }],
            isError: true,
          };
        }
        // Let tree-hugger handle file reading and language detection
        tree = parse(resolvedPath, { language: args.language });
        sourceCode = readFileSync(resolvedPath, 'utf-8');
        filePath = resolvedPath;
      } else {
        sourceCode = args.source;
        tree = parse(sourceCode, { language: args.language });
      }
      
      this.currentAST = {
        tree,
        filePath,
        sourceCode,
        language: args.language || 'auto-detected',
        timestamp: new Date(),
      };
  
      return {
        content: [{
          type: "text",
          text: `Successfully parsed ${filePath || 'code string'}\n` +
                `Language: ${this.currentAST.language}\n` +
                `Lines: ${sourceCode.split('\n').length}\n` +
                `Characters: ${sourceCode.length}\n` +
                `Parse errors: ${tree.root.hasError ? 'Yes' : 'No'}\n` +
                `Root node type: ${tree.root.type}`,
        }],
      };
    } catch (error) {
      return {
        content: [{
          type: "text",
          text: `Error parsing code: ${error instanceof Error ? error.message : String(error)}`,
        }],
        isError: true,
      };
    }
  }

• src/index.ts:183-200 (schema)

  Input schema defining parameters for the parse_code tool: source (required string), isFilePath (optional boolean), language (optional string).

  inputSchema: {
    type: "object",
    properties: {
      source: { 
        type: "string", 
        description: "File path (./src/app.js) or code string ('const x = 1;')" 
      },
      isFilePath: {
        type: "boolean",
        description: "Whether source is a file path (true) or code string (false). Defaults to auto-detect."
      },
      language: {
        type: "string",
        description: "Language to use (javascript, typescript, jsx, tsx). Auto-detected if not provided."
      }
    },
    required: ["source"],
  },

• src/index.ts:180-201 (registration)

  Registration of the parse_code tool in the tools list returned by ListToolsRequestSchema handler, including name, description, and inputSchema.

  {
    name: "parse_code",
    description: "Parse JavaScript/TypeScript code from file or string and load it into the AST state. Must be called before using other analysis tools.\n\nExamples:\n• Parse a React component: parse_code('./src/UserProfile.jsx')\n• Parse code string: parse_code('function hello() { return \"world\"; }')\n• Parse with explicit language: parse_code('./config.js', language='javascript')\n• Analyze legacy code: parse_code('./old-script.js') then use other tools to understand structure\n• Code review prep: parse_code('./feature.ts') then get_functions() to review all functions",
    inputSchema: {
      type: "object",
      properties: {
        source: { 
          type: "string", 
          description: "File path (./src/app.js) or code string ('const x = 1;')" 
        },
        isFilePath: {
          type: "boolean",
          description: "Whether source is a file path (true) or code string (false). Defaults to auto-detect."
        },
        language: {
          type: "string",
          description: "Language to use (javascript, typescript, jsx, tsx). Auto-detected if not provided."
        }
      },
      required: ["source"],
    },
  },