SureChEMBL MCP Server

Instructions

Implementation Reference

• src/index.ts:803-843 (handler)

  The main handler function that validates input arguments, calls the SureChEMBL API endpoint '/service/chemical/image' with structure notation and dimensions, receives image as binary data, encodes it as base64 PNG data URI, and returns structured JSON response.

  private async handleGetChemicalImage(args: any) {
    if (!isValidImageArgs(args)) {
      throw new McpError(ErrorCode.InvalidParams, 'Invalid image arguments');
    }
  
    try {
      const height = args.height || 200;
      const width = args.width || 200;
  
      const response = await this.apiClient.get('/service/chemical/image', {
        params: {
          structure: args.structure,
          height: height,
          width: width
        },
        responseType: 'arraybuffer'
      });
  
      // Convert binary data to base64 for JSON response
      const base64Image = Buffer.from(response.data).toString('base64');
  
      return {
        content: [
          {
            type: 'text',
            text: JSON.stringify({
              structure: args.structure,
              image_data: `data:image/png;base64,${base64Image}`,
              dimensions: { width, height },
              message: 'Chemical structure image generated successfully'
            }, null, 2),
          },
        ],
      };
    } catch (error) {
      throw new McpError(
        ErrorCode.InternalError,
        `Failed to generate chemical image: ${error instanceof Error ? error.message : 'Unknown error'}`
      );
    }
  }

• src/index.ts:438-446 (schema)

  JSON schema defining input parameters for the tool: required 'structure' string (SMILES or notation), optional 'height' and 'width' numbers (50-1000).

  inputSchema: {
    type: 'object',
    properties: {
      structure: { type: 'string', description: 'SMILES string or other structure notation' },
      height: { type: 'number', description: 'Image height in pixels (default: 200)', minimum: 50, maximum: 1000 },
      width: { type: 'number', description: 'Image width in pixels (default: 200)', minimum: 50, maximum: 1000 },
    },
    required: ['structure'],
  },

• src/index.ts:435-447 (registration)

  Full tool registration entry in the ListToolsRequestSchema handler's tools array, including name, description, and input schema.

  {
    name: 'get_chemical_image',
    description: 'Generate chemical structure image from SMILES or other structure notation',
    inputSchema: {
      type: 'object',
      properties: {
        structure: { type: 'string', description: 'SMILES string or other structure notation' },
        height: { type: 'number', description: 'Image height in pixels (default: 200)', minimum: 50, maximum: 1000 },
        width: { type: 'number', description: 'Image width in pixels (default: 200)', minimum: 50, maximum: 1000 },
      },
      required: ['structure'],
    },
  },

• src/index.ts:562-563 (registration)

  Switch case in CallToolRequestSchema handler that dispatches execution to the specific tool handler.

  case 'get_chemical_image':
    return await this.handleGetChemicalImage(args);

• src/index.ts:129-140 (helper)

  Type guard function validating tool input arguments matching the schema: non-empty structure string, optional height/width in 1-1000 range.

  const isValidImageArgs = (
    args: any
  ): args is { structure: string; height?: number; width?: number } => {
    return (
      typeof args === 'object' &&
      args !== null &&
      typeof args.structure === 'string' &&
      args.structure.length > 0 &&
      (args.height === undefined || (typeof args.height === 'number' && args.height > 0 && args.height <= 1000)) &&
      (args.width === undefined || (typeof args.width === 'number' && args.width > 0 && args.width <= 1000))
    );
  };