Tree-Hugger-JS MCP Server

Instructions

Implementation Reference

• src/index.ts:781-828 (handler)

  The main handler function that performs the rename operation using tree-hugger-js transform API. Handles preview mode, updates AST and source code, records in transform history, and returns result or preview.

  private async renameIdentifier(args: { oldName: string; newName: string; preview?: boolean }) {
    if (!this.currentAST) {
      return {
        content: [{
          type: "text",
          text: "No AST loaded. Please use parse_code first.",
        }],
        isError: true,
      };
    }
  
    try {
      const transformed = this.currentAST.tree.transform()
        .rename(args.oldName, args.newName);
  
      const result = transformed.toString();
      
      if (!args.preview) {
        this.currentAST.sourceCode = result;
        this.currentAST.tree = parse(result);
        this.currentAST.timestamp = new Date();
      }
  
      const transformResult: TransformResult = {
        operation: "rename_identifier",
        parameters: { oldName: args.oldName, newName: args.newName },
        preview: result.slice(0, 500) + (result.length > 500 ? '...' : ''),
        timestamp: new Date(),
      };
      
      this.transformHistory.push(transformResult);
  
      return {
        content: [{
          type: "text",
          text: `${args.preview ? 'Preview: ' : ''}Renamed "${args.oldName}" to "${args.newName}"\n\n${args.preview ? 'Preview:\n' : 'Result:\n'}${result}`,
        }],
      };
    } catch (error) {
      return {
        content: [{
          type: "text",
          text: `Error renaming identifier: ${error instanceof Error ? error.message : String(error)}`,
        }],
        isError: true,
      };
    }
  }

• src/index.ts:284-301 (schema)

  Input schema defining parameters oldName (string, required), newName (string, required), preview (boolean, optional) for the rename_identifier tool.

  inputSchema: {
    type: "object",
    properties: {
      oldName: {
        type: "string",
        description: "Current identifier name to find and replace"
      },
      newName: {
        type: "string", 
        description: "New identifier name (should be valid JavaScript identifier)"
      },
      preview: {
        type: "boolean",
        description: "Return preview only without applying changes (default: false). Always preview first for safety."
      }
    },
    required: ["oldName", "newName"],
  },

• src/index.ts:281-302 (registration)

  Tool registration in ListToolsRequestSchema handler, including name, detailed description with examples, and input schema.

  {
    name: "rename_identifier", 
    description: "Intelligently rename all occurrences of an identifier throughout the code. Avoids renaming in strings/comments.\n\nExamples:\n• Refactor function names: rename_identifier('fetchData', 'fetchUserData')\n• Improve variable names: rename_identifier('data', 'userData')\n• Update class names: rename_identifier('Manager', 'UserManager')\n• API consistency: rename_identifier('getUserInfo', 'fetchUserInfo')\n• Preview first: rename_identifier('oldName', 'newName', {preview: true})\n• Legacy code update: rename_identifier('XMLHttpRequest', 'fetch')",
    inputSchema: {
      type: "object",
      properties: {
        oldName: {
          type: "string",
          description: "Current identifier name to find and replace"
        },
        newName: {
          type: "string", 
          description: "New identifier name (should be valid JavaScript identifier)"
        },
        preview: {
          type: "boolean",
          description: "Return preview only without applying changes (default: false). Always preview first for safety."
        }
      },
      required: ["oldName", "newName"],
    },
  },

• src/index.ts:431-432 (registration)

  Dispatcher case in CallToolRequestSchema handler that routes the tool call to the renameIdentifier method.

  case "rename_identifier":
    return await this.renameIdentifier(args as { oldName: string; newName: string; preview?: boolean });