Walrus MCP Server

Instructions

Implementation Reference

• src/index.ts:192-203 (handler)

  MCP tool handler for 'get_blob_info': parses input using schema, calls walrusClient.getBlobInfo, and returns JSON stringified result.

  case 'get_blob_info': {
    const { blobId } = GetBlobInfoSchema.parse(args);
    const result = await walrusClient.getBlobInfo(blobId);
    return {
      content: [
        {
          type: 'text',
          text: JSON.stringify(result, null, 2),
        },
      ],
    };
  }

• src/index.ts:47-49 (schema)

  Zod schema for validating input arguments to get_blob_info tool (blobId: string).

  const GetBlobInfoSchema = z.object({
    blobId: z.string().describe('The blob ID to get information about'),
  });

• src/index.ts:116-129 (registration)

  Registration of 'get_blob_info' tool in the ListTools response, including name, description, and input schema.

  {
    name: 'get_blob_info',
    description: 'Get information about a blob (size, availability, etc.)',
    inputSchema: {
      type: 'object',
      properties: {
        blobId: {
          type: 'string',
          description: 'The blob ID to get information about',
        },
      },
      required: ['blobId'],
    },
  },

• src/walrus-client.ts:128-151 (helper)

  Core implementation of getBlobInfo: performs HEAD request to aggregator to get blob metadata like size, assumes certified if accessible.

  async getBlobInfo(blobId: string): Promise<BlobInfo> {
    try {
      // Try to get blob head information
      const response = await this.httpClient.head(`${this.config.aggregatorUrl}/v1/${blobId}`);
      
      const size = parseInt(response.headers['content-length'] || '0');
      
      return {
        blobId,
        size,
        encodedSize: size, // Approximate, actual encoded size may differ
        storageId: blobId,
        certified: true, // If we can access it, it's certified
      };
    } catch (error) {
      if (axios.isAxiosError(error)) {
        if (error.response?.status === 404) {
          throw new Error(`Blob not found: ${blobId}`);
        }
        throw new Error(`Failed to get blob info: ${error.response?.data?.error || error.message}`);
      }
      throw new Error(`Failed to get blob info: ${error instanceof Error ? error.message : String(error)}`);
    }
  }