exif-mcp

Instructions

Implementation Reference

• src/tools/index.ts:181-195 (handler)

  The core handler function for the 'orientation' tool. Loads the image buffer using loadImage, extracts the orientation value using exifr.orientation(buf), and returns it or an error response.
  async (args, extra) => { try { const { image } = args; const buf = await loadImage(image); const orientation = await exifr.orientation(buf); if (orientation === undefined) { return createErrorResponse('No orientation metadata found in image'); } return createSuccessResponse({ orientation }); } catch (error) { return createErrorResponse(`Error reading orientation: ${error instanceof Error ? error.message : String(error)}`); } }
• src/tools/index.ts:54-60 (schema)

  Zod schema defining the input structure for the image source parameter used by the 'orientation' tool.
  const ImageSourceSchema = z.object({ kind: z.enum(['path', 'url', 'base64', 'buffer']), path: z.string().optional(), url: z.string().optional(), data: z.string().optional(), buffer: z.string().optional() });
• src/tools/index.ts:176-197 (registration)

  Registers the 'orientation' tool with the MCP server, specifying name, description, input schema, and handler function. Also stores reference in tools object.
  const orientationTool = server.tool('orientation', "Get image orientation value (1-8)", { image: ImageSourceSchema }, async (args, extra) => { try { const { image } = args; const buf = await loadImage(image); const orientation = await exifr.orientation(buf); if (orientation === undefined) { return createErrorResponse('No orientation metadata found in image'); } return createSuccessResponse({ orientation }); } catch (error) { return createErrorResponse(`Error reading orientation: ${error instanceof Error ? error.message : String(error)}`); } } ); tools['orientation'] = orientationTool;
• src/tools/loaders.ts:11-72 (helper)

  Supporting helper that loads image data from path, URL, base64, or buffer into a Buffer/Uint8Array, used by the orientation handler.
  export async function loadImage(src: ImageSourceType): Promise<Buffer | Uint8Array> { try { switch (src.kind) { case 'path': if (!src.path) { throw new Error('Path is required for kind="path"'); } return await fs.promises.readFile(src.path); case 'url': if (!src.url) { throw new Error('URL is required for kind="url"'); } if (src.url.startsWith('file://')) { // Handle file:// URLs by converting to filesystem path const filePath = fileURLToPath(src.url); return await fs.promises.readFile(filePath); } else { // Handle HTTP/HTTPS URLs const response = await fetch(src.url); if (!response.ok) { throw new Error(`Failed to fetch URL: ${response.status} ${response.statusText}`); } return new Uint8Array(await response.arrayBuffer()); } case 'base64': if (!src.data) { throw new Error('Data is required for kind="base64"'); } // Check for potential oversized base64 string (>30MB) if (src.data.length > 40000000) { // ~30MB in base64 throw new Error('PayloadTooLarge: Base64 data exceeds 30MB limit'); } // Handle data URIs or raw base64 if (src.data.startsWith('data:')) { const base64Data = src.data.split(',')[1]; return Buffer.from(base64Data, 'base64'); } else { return Buffer.from(src.data, 'base64'); } case 'buffer': if (!src.buffer) { throw new Error('Buffer is required for kind="buffer"'); } return Buffer.from(src.buffer, 'base64'); default: // This should never happen due to type constraints, but TypeScript needs it throw new Error(`Unsupported image source kind: ${(src as any).kind}`); } } catch (error) { if (error instanceof Error) { throw new Error(`Failed to load image: ${error.message}`); } throw error; } }
• src/tools/index.ts:18-27 (helper)

  Helper function used by the orientation handler to format successful MCP tool responses.
  function createSuccessResponse(data: any) { return { content: [ { type: "text" as const, text: typeof data === 'string' ? data : JSON.stringify(data, null, 2) } ] }; }