mongo-count-documents

Count documents in a MongoDB collection using a query filter to retrieve specific data counts from your database.

Instructions

Count documents in a MongoDB collection

Input Schema

TableJSON Schema

Name	Required	Description
`database`	Yes	Database name
`collection`	Yes	Collection name
`filter`	No	Query filter as JSON object (optional)

Implementation Reference

src/index.ts:272-290 (handler)

Handler function that ensures database connection, retrieves the collection, counts documents matching the optional filter using countDocuments, and returns the count in a text response.

async ({ database: dbName, collection: collectionName, filter = {} }) => {
  try {
    const db = await ensureConnection(dbName);
    const collection: Collection = db.collection(collectionName);
    
    const count = await collection.countDocuments(filter);
    
    return {
      content: [
        {
          type: "text",
          text: `Found ${count} document(s) matching the filter`,
        },
      ],
    };
  } catch (error) {
    throw new Error(`Failed to count documents: ${error instanceof Error ? error.message : 'Unknown error'}`);
  }
}

src/index.ts:267-271 (schema)

Zod schema defining input parameters: database name, collection name, and optional filter object.

{
  database: z.string().describe("Database name"),
  collection: z.string().describe("Collection name"),
  filter: z.record(z.any()).optional().describe("Query filter as JSON object (optional)"),
},

src/index.ts:264-291 (registration)

Registration of the 'mongo-count-documents' tool with the MCP server, including description, input schema, and inline handler function.

server.tool(
  "mongo-count-documents",
  "Count documents in a MongoDB collection",
  {
    database: z.string().describe("Database name"),
    collection: z.string().describe("Collection name"),
    filter: z.record(z.any()).optional().describe("Query filter as JSON object (optional)"),
  },
  async ({ database: dbName, collection: collectionName, filter = {} }) => {
    try {
      const db = await ensureConnection(dbName);
      const collection: Collection = db.collection(collectionName);
      
      const count = await collection.countDocuments(filter);
      
      return {
        content: [
          {
            type: "text",
            text: `Found ${count} document(s) matching the filter`,
          },
        ],
      };
    } catch (error) {
      throw new Error(`Failed to count documents: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }
);

MCP Server Boilerplate