ChEMBL MCP Server

Instructions

Implementation Reference

• src/index.ts:976-987 (handler)

  The main handler function that implements the get_target_info tool. It validates input, fetches target data from ChEMBL API endpoint /target/{chembl_id}.json, and returns formatted JSON response.

  private async handleGetTargetInfo(args: any) {
    if (!isValidChemblIdArgs(args)) {
      throw new McpError(ErrorCode.InvalidParams, 'Invalid arguments');
    }
  
    try {
      const response = await this.apiClient.get(`/target/${args.chembl_id}.json`);
      return { content: [{ type: 'text', text: JSON.stringify(response.data, null, 2) }] };
    } catch (error) {
      throw new McpError(ErrorCode.InternalError, `Failed to get target info: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

• src/index.ts:472-482 (registration)

  Tool registration in ListToolsRequestSchema handler, defining name, description, and input schema.

  {
    name: 'get_target_info',
    description: 'Get detailed information for a specific target by ChEMBL target ID',
    inputSchema: {
      type: 'object',
      properties: {
        chembl_id: { type: 'string', description: 'ChEMBL target ID (e.g., CHEMBL2095173)' },
      },
      required: ['chembl_id'],
    },
  },

• src/index.ts:758-759 (registration)

  Dispatch/registration in CallToolRequestSchema switch statement, routing calls to the handler.

  case 'get_target_info':
    return await this.handleGetTargetInfo(args);

• src/index.ts:90-99 (schema)

  Input validation helper function used by the handler to check chembl_id parameter.

  const isValidChemblIdArgs = (
    args: any
  ): args is { chembl_id: string } => {
    return (
      typeof args === 'object' &&
      args !== null &&
      typeof args.chembl_id === 'string' &&
      args.chembl_id.length > 0
    );
  };

• src/index.ts:37-49 (schema)

  TypeScript interface defining the structure of target information returned by ChEMBL API.

  interface TargetInfo {
    target_chembl_id: string;
    pref_name: string;
    target_type: string;
    organism: string;
    species_group_flag: boolean;
    target_components?: Array<{
      component_id: number;
      component_type: string;
      accession?: string;
      sequence?: string;
    }>;
  }