MCP PC Control Server

Instructions

Implementation Reference

• src/index.ts:307-340 (handler)

  The handler for the 'edit_file' tool. Reads the target file, applies each specified edit by replacing 'oldText' with 'newText' (ensuring 'oldText' exists first), overwrites the file with the modified content, generates a simple unified diff using the helper function, and returns the diff.

  case "edit_file": {
    const filePath = args.path as string;
    const edits = args.edits as Array<{
      oldText: string;
      newText: string;
    }>;
  
    let content = await fs.readFile(filePath, "utf-8");
    const originalContent = content;
  
    // Apply each edit
    for (const edit of edits) {
      if (!content.includes(edit.oldText)) {
        throw new Error(
          `Could not find text to replace: ${edit.oldText.substring(0, 100)}...`
        );
      }
      content = content.replace(edit.oldText, edit.newText);
    }
  
    await fs.writeFile(filePath, content, "utf-8");
  
    // Generate diff
    const diff = generateDiff(originalContent, content, filePath);
  
    return {
      content: [
        {
          type: "text",
          text: `Successfully edited ${filePath}\n\n${diff}`,
        },
      ],
    };
  }

• src/index.ts:55-82 (schema)

  Input schema for the 'edit_file' tool, defining required parameters: 'path' (string) and 'edits' (array of objects with 'oldText' and 'newText').

  inputSchema: {
    type: "object",
    properties: {
      path: {
        type: "string",
        description: "The path to the file to edit",
      },
      edits: {
        type: "array",
        description: "Array of edit operations to apply",
        items: {
          type: "object",
          properties: {
            oldText: {
              type: "string",
              description: "The exact text to search for (can be multiple lines)",
            },
            newText: {
              type: "string",
              description: "The text to replace it with",
            },
          },
          required: ["oldText", "newText"],
        },
      },
    },
    required: ["path", "edits"],
  },

• src/index.ts:52-83 (registration)

  Registration of the 'edit_file' tool in the TOOLS array, which is returned by the listTools handler. Includes name, description, and input schema.

  {
    name: "edit_file",
    description: "Make line-based edits to a text file. Provide original lines and their replacements. Returns a git-style diff showing the changes made. Each edit replaces exact line sequences with new content.",
    inputSchema: {
      type: "object",
      properties: {
        path: {
          type: "string",
          description: "The path to the file to edit",
        },
        edits: {
          type: "array",
          description: "Array of edit operations to apply",
          items: {
            type: "object",
            properties: {
              oldText: {
                type: "string",
                description: "The exact text to search for (can be multiple lines)",
              },
              newText: {
                type: "string",
                description: "The text to replace it with",
              },
            },
            required: ["oldText", "newText"],
          },
        },
      },
      required: ["path", "edits"],
    },
  },

• src/index.ts:523-552 (helper)

  Helper function 'generateDiff' that creates a simple git-style unified diff between original and modified file contents. Called by the edit_file handler to include the diff in the response.

  function generateDiff(
    original: string,
    modified: string,
    filepath: string
  ): string {
    const originalLines = original.split("\n");
    const modifiedLines = modified.split("\n");
  
    let diff = `--- ${filepath}\n+++ ${filepath}\n`;
    let lineNum = 0;
  
    while (
      lineNum < originalLines.length ||
      lineNum < modifiedLines.length
    ) {
      if (originalLines[lineNum] !== modifiedLines[lineNum]) {
        diff += `@@ -${lineNum + 1} +${lineNum + 1} @@\n`;
  
        if (lineNum < originalLines.length) {
          diff += `- ${originalLines[lineNum]}\n`;
        }
        if (lineNum < modifiedLines.length) {
          diff += `+ ${modifiedLines[lineNum]}\n`;
        }
      }
      lineNum++;
    }
  
    return diff;
  }