read_file

Instructions

Implementation Reference

• src/index.ts:167-180 (registration)

  Tool registration with name 'read_file', description, and JSON Schema input definition requiring 'path' and accepting optional 'start_line', 'end_line', and 'workspace_root'.

  {
    name: "read_file",
    description: "Read the contents of a file. Optionally specify a line range.",
    inputSchema: {
      type: "object",
      properties: {
        path: { type: "string", description: "File path (absolute or relative to workspace root)" },
        start_line: { type: "number", description: "First line to read (1-indexed, inclusive)" },
        end_line: { type: "number", description: "Last line to read (1-indexed, inclusive)" },
        workspace_root: { type: "string", description: "Workspace root directory (optional)" },
      },
      required: ["path"],
    },
  },

• src/index.ts:434-442 (handler)

  Handler that resolves the file path, calls readFileLines with optional line range, and returns text content result.

  case "read_file": {
    const filePath = resolveWorkspacePath(a.path as string, a.workspace_root as string | undefined);
    const content = await readFileLines(
      filePath,
      a.start_line as number | undefined,
      a.end_line as number | undefined
    );
    return { content: [{ type: "text", text: content }] };
  }

• src/index.ts:65-84 (helper)

  Helper function that reads a file. If no line range given, reads entire file via fs/promises readFile. Otherwise streams the file line-by-line and returns only the requested lines.

  async function readFileLines(
    filePath: string,
    startLine?: number,
    endLine?: number
  ): Promise<string> {
    if (startLine === undefined && endLine === undefined) {
      return readFile(filePath, "utf-8");
    }
    const lines: string[] = [];
    const rl = createInterface({ input: createReadStream(filePath), crlfDelay: Infinity });
    let lineNum = 1;
    for await (const line of rl) {
      if (startLine === undefined || lineNum >= startLine) {
        if (endLine === undefined || lineNum <= endLine) lines.push(line);
        else break;
      }
      lineNum++;
    }
    return lines.join("\n");
  }

• src/index.ts:59-63 (helper)

  Helper that resolves a potentially relative file path against a workspace root (or cwd). Absolute paths are returned as-is.

  function resolveWorkspacePath(filePath: string, workspaceRoot?: string): string {
    if (filePath.startsWith("/") || /^[A-Za-z]:/.test(filePath)) return filePath;
    const base = workspaceRoot ?? process.cwd();
    return resolve(join(base, filePath));
  }