MCP SmallEdit

Instructions

Implementation Reference

• src/index.ts:700-737 (handler)

  Handler for 'line_edit' tool: destructures input params, constructs appropriate sed command based on action (replace, delete, insert_after, insert_before), executes it with backup, returns success message.

        case 'line_edit': {
          const { file, lineNumber, lineRange, action, content } = args;
          
          if (!existsSync(file)) {
            throw new Error(`File not found: ${file}`);
          }
          
          let sedCmd = 'sed -i.bak ';
          const range = lineRange || `${lineNumber}`;
          
          switch (action) {
            case 'replace':
              sedCmd += `'${range}s/.*/${content}/' '${file}'`;
              break;
            case 'delete':
              sedCmd += `'${range}d' '${file}'`;
              break;
            case 'insert_after':
              sedCmd += `'${range}a\\
  ${content}' '${file}'`;
              break;
            case 'insert_before':
              sedCmd += `'${range}i\\
  ${content}' '${file}'`;
              break;
            default:
              throw new Error(`Unknown action: ${action}`);
          }
          
          await execAsync(sedCmd);
          
          return {
            content: [{
              type: 'text',
              text: `Successfully performed ${action} on line(s) ${range} in ${file}`
            }]
          };
        }

• src/index.ts:147-172 (schema)

  Input schema definition for line_edit tool, specifying properties and validation rules.

  inputSchema: {
    type: 'object',
    properties: {
      file: {
        type: 'string',
        description: 'File to edit'
      },
      lineNumber: {
        type: 'number',
        description: 'Line number to edit (1-based)'
      },
      lineRange: {
        type: 'string',
        description: 'Line range (e.g., "10,20" or "5,$")'
      },
      action: {
        type: 'string',
        enum: ['replace', 'delete', 'insert_after', 'insert_before'],
        description: 'Action to perform'
      },
      content: {
        type: 'string',
        description: 'New content (for replace/insert actions)'
      }
    },
    required: ['file', 'action']

• src/index.ts:144-174 (registration)

  Registration of the 'line_edit' tool in the tools array passed to server.setTools.

  {
    name: 'line_edit',
    description: 'Edit specific lines by number or range',
    inputSchema: {
      type: 'object',
      properties: {
        file: {
          type: 'string',
          description: 'File to edit'
        },
        lineNumber: {
          type: 'number',
          description: 'Line number to edit (1-based)'
        },
        lineRange: {
          type: 'string',
          description: 'Line range (e.g., "10,20" or "5,$")'
        },
        action: {
          type: 'string',
          enum: ['replace', 'delete', 'insert_after', 'insert_before'],
          description: 'Action to perform'
        },
        content: {
          type: 'string',
          description: 'New content (for replace/insert actions)'
        }
      },
      required: ['file', 'action']
    }
  },

• src/index.ts:425-446 (helper)

  Help documentation and usage examples for the line_edit tool in the helpContent object.

    line_edit: `line_edit - Line-specific operations
  ==================================
  Edit, delete, or insert at specific line numbers.
  
  Examples:
    // Replace line 10
    line_edit({ file: "list.txt", lineNumber: 10, action: "replace", content: "New line 10" })
    
    // Delete lines 5-15
    line_edit({ file: "data.txt", lineRange: "5,15", action: "delete" })
    
    // Insert after line 1
    line_edit({ file: "imports.js", lineNumber: 1, action: "insert_after", content: "import React from 'react';" })
    
    // Insert before last line
    line_edit({ file: "footer.html", lineRange: "$", action: "insert_before", content: "<!-- Updated -->" })
  
  Ranges:
  - Single line: lineNumber: 42
  - Range: lineRange: "10,20" 
  - To end: lineRange: "5,$"
  `,