ERPNext MCP Server

Instructions

Implementation Reference

• src/index.ts:612-669 (handler)

  The handler for the 'get_doctype_fields' tool within the CallToolRequestSchema switch statement. It retrieves a sample document for the specified doctype using getDocList, extracts field names, types, and sample values from it, and returns them as JSON.

  case "get_doctype_fields": {
    if (!erpnext.isAuthenticated()) {
      return {
        content: [{
          type: "text",
          text: "Not authenticated with ERPNext. Please configure API key authentication."
        }],
        isError: true
      };
    }
    
    const doctype = String(request.params.arguments?.doctype);
    
    if (!doctype) {
      throw new McpError(
        ErrorCode.InvalidParams,
        "Doctype is required"
      );
    }
    
    try {
      // Get a sample document to understand the fields
      const documents = await erpnext.getDocList(doctype, {}, ["*"], 1);
      
      if (!documents || documents.length === 0) {
        return {
          content: [{
            type: "text",
            text: `No documents found for ${doctype}. Cannot determine fields.`
          }],
          isError: true
        };
      }
      
      // Extract field names from the first document
      const sampleDoc = documents[0];
      const fields = Object.keys(sampleDoc).map(field => ({
        fieldname: field,
        value: typeof sampleDoc[field],
        sample: sampleDoc[field]?.toString()?.substring(0, 50) || null
      }));
      
      return {
        content: [{
          type: "text",
          text: JSON.stringify(fields, null, 2)
        }]
      };
    } catch (error: any) {
      return {
        content: [{
          type: "text",
          text: `Failed to get fields for ${doctype}: ${error?.message || 'Unknown error'}`
        }],
        isError: true
      };
    }
  }

• src/index.ts:335-348 (registration)

  Registration of the 'get_doctype_fields' tool in the ListToolsRequestSchema handler, including its name, description, and input schema.

  {
    name: "get_doctype_fields",
    description: "Get fields list for a specific DocType",
    inputSchema: {
      type: "object",
      properties: {
        doctype: {
          type: "string",
          description: "ERPNext DocType (e.g., Customer, Item)"
        }
      },
        required: ["doctype"]
    }
  },

• src/index.ts:338-347 (schema)

  Input schema definition for the 'get_doctype_fields' tool, specifying the required 'doctype' parameter.

  inputSchema: {
    type: "object",
    properties: {
      doctype: {
        type: "string",
        description: "ERPNext DocType (e.g., Customer, Item)"
      }
    },
      required: ["doctype"]
  }

• src/index.ts:81-102 (helper)

  ERPNextClient.getDocList method used by the handler to fetch a sample document and infer fields.

  // Get list of documents for a doctype
  async getDocList(doctype: string, filters?: Record<string, any>, fields?: string[], limit?: number): Promise<any[]> {
    try {
      let params: Record<string, any> = {};
      
      if (fields && fields.length) {
        params['fields'] = JSON.stringify(fields);
      }
      
      if (filters) {
        params['filters'] = JSON.stringify(filters);
      }
      
      if (limit) {
        params['limit_page_length'] = limit;
      }
      
      const response = await this.axiosInstance.get(`/api/resource/${doctype}`, { params });
      return response.data.data;
    } catch (error: any) {
      throw new Error(`Failed to get ${doctype} list: ${error?.message || 'Unknown error'}`);
    }