get_node_at_position

Retrieve detailed AST node information at a specific cursor position for debugging, code analysis, refactoring, and IDE integration.

Instructions

Get detailed AST node information at a specific cursor position. Perfect for debugging and precise analysis.

Examples: • Debug syntax errors: get_node_at_position(15, 23) to understand what's at error location • Understand code structure: get_node_at_position(line, col) to see AST node type at cursor • Refactoring assistance: get_node_at_position(line, col) to identify exact node before transformation • IDE integration: get_node_at_position(line, col) for hover information • Pattern development: get_node_at_position(line, col) to understand node structure for pattern writing

Input Schema

TableJSON Schema

Name	Required	Description	Default
`line`	Yes	Line number (1-based) - the line where cursor is positioned
`column`	Yes	Column number (0-based) - the character position within the line

Implementation Reference

src/index.ts:961-1014 (handler)

The primary handler function that executes the tool logic: checks for loaded AST, uses tree.nodeAt(line, column) to find the node, builds a detailed nodeInfo object, and returns formatted text response.

private async getNodeAtPosition(args: { line: number; column: number }) {
  if (!this.currentAST) {
    return {
      content: [{
        type: "text",
        text: "No AST loaded. Please use parse_code first.",
      }],
      isError: true,
    };
  }

  try {
    const node = this.currentAST.tree.nodeAt(args.line, args.column);
    
    if (!node) {
      return {
        content: [{
          type: "text",
          text: `No node found at position ${args.line}:${args.column}`,
        }],
      };
    }

    const nodeInfo = {
      type: node.type,
      text: node.text.length > 200 ? node.text.slice(0, 200) + '...' : node.text,
      line: node.line,
      column: node.column,
      name: node.name,
      startPosition: node.startPosition,
      endPosition: node.endPosition,
      parent: node.parent ? {
        type: node.parent.type,
        name: node.parent.name,
      } : null,
      childrenCount: node.children.length,
    };

    return {
      content: [{
        type: "text",
        text: `Node at position ${args.line}:${args.column}:\n${JSON.stringify(nodeInfo, null, 2)}`,
      }],
    };
  } catch (error) {
    return {
      content: [{
        type: "text",
        text: `Error getting node at position: ${error instanceof Error ? error.message : String(error)}`,
      }],
      isError: true,
    };
  }
}

src/index.ts:351-364 (schema)

Input schema defining the required parameters: line (1-based number) and column (0-based number).

inputSchema: {
  type: "object",
  properties: {
    line: {
      type: "number",
      description: "Line number (1-based) - the line where cursor is positioned"
    },
    column: {
      type: "number", 
      description: "Column number (0-based) - the character position within the line"
    }
  },
  required: ["line", "column"],
},

src/index.ts:349-365 (registration)

Tool registration entry in the MCP server's tools list, including name, description, and input schema.

  name: "get_node_at_position",
  description: "Get detailed AST node information at a specific cursor position. Perfect for debugging and precise analysis.\n\nExamples:\n• Debug syntax errors: get_node_at_position(15, 23) to understand what's at error location\n• Understand code structure: get_node_at_position(line, col) to see AST node type at cursor\n• Refactoring assistance: get_node_at_position(line, col) to identify exact node before transformation\n• IDE integration: get_node_at_position(line, col) for hover information\n• Pattern development: get_node_at_position(line, col) to understand node structure for pattern writing",
  inputSchema: {
    type: "object",
    properties: {
      line: {
        type: "number",
        description: "Line number (1-based) - the line where cursor is positioned"
      },
      column: {
        type: "number", 
        description: "Column number (0-based) - the character position within the line"
      }
    },
    required: ["line", "column"],
  },
},

src/index.ts:440-441 (registration)
Dispatch case in the central request handler switch that routes tool calls to the getNodeAtPosition method.
```
case "get_node_at_position":
  return await this.getNodeAtPosition(args as { line: number; column: number });
```

Tree-Hugger-JS MCP Server