MCP-MongoDB-MySQL-Server

Instructions

Implementation Reference

• src/index.ts:977-1009 (handler)

  Executes the mongodb_find tool: ensures MongoDB connection, validates collection name, constructs filter and options (limit, skip, sort), performs find query on the collection, and returns results as JSON string.

  private async handleMongoDBFind(args: any) {
    await this.ensureMongoConnection();
  
    if (!args.collection) {
      throw new McpError(ErrorCode.InvalidParams, 'Collection name is required');
    }
  
    try {
      const collection = this.mongoDB!.collection(args.collection);
      const filter = args.filter || {};
      const options: any = {};
      
      if (args.limit) options.limit = args.limit;
      if (args.skip) options.skip = args.skip;
      if (args.sort) options.sort = args.sort;
  
      const documents = await collection.find(filter, options).toArray();
      return {
        content: [
          {
            type: 'text',
            text: JSON.stringify(documents, null, 2),
          },
        ],
      };
    } catch (error) {
      throw new McpError(
        ErrorCode.InternalError,
        `Failed to find documents: ${getErrorMessage(error)}`
      );
    }
  }

• src/index.ts:411-440 (schema)

  Defines the input schema for the mongodb_find tool, specifying parameters like collection (required), filter, limit, skip, and sort (all optional).

  inputSchema: {
    type: 'object',
    properties: {
      collection: {
        type: 'string',
        description: 'Collection name',
      },
      filter: {
        type: 'object',
        description: 'MongoDB query filter',
        optional: true
      },
      limit: {
        type: 'number',
        description: 'Maximum number of documents to return',
        optional: true
      },
      skip: {
        type: 'number',
        description: 'Number of documents to skip',
        optional: true
      },
      sort: {
        type: 'object',
        description: 'Sort criteria',
        optional: true
      }
    },
    required: ['collection'],
  },

• src/index.ts:408-441 (registration)

  Registers the mongodb_find tool in the MCP server's tools list, providing name, description, and input schema for the ListTools request.

  {
    name: 'mongodb_find',
    description: 'Find documents in a MongoDB collection',
    inputSchema: {
      type: 'object',
      properties: {
        collection: {
          type: 'string',
          description: 'Collection name',
        },
        filter: {
          type: 'object',
          description: 'MongoDB query filter',
          optional: true
        },
        limit: {
          type: 'number',
          description: 'Maximum number of documents to return',
          optional: true
        },
        skip: {
          type: 'number',
          description: 'Number of documents to skip',
          optional: true
        },
        sort: {
          type: 'object',
          description: 'Sort criteria',
          optional: true
        }
      },
      required: ['collection'],
    },
  },

• src/index.ts:556-557 (registration)

  Switch case in the CallToolRequestSchema handler that routes mongodb_find tool calls to the handleMongoDBFind method.

  case 'mongodb_find':
    return await this.handleMongoDBFind(request.params.arguments);