# MongoDB tools in Cogny Cogny's MongoDB integration exposes 8 tools (8 read) to an AI agent over MCP. The same tools are available on every plan, from your own AI client or inside the Cogny app. - **Read** (8): only reads data. - **Write** (0): creates or changes something. - **Destructive** (0): deletes, removes or replaces something. Over MCP your own AI client asks before it runs a write. To take a tool away from your agent, block it in Settings → Integrations. ## Notes MongoDB connects with the connection string of a database user, for example `mongodb+srv://cogny_reader:@cluster0.abcde.mongodb.net/shop` from Atlas → Connect → Drivers, or a `mongodb://` string for a self-hosted server. The database after the host (`/shop`) is the default for every tool; each tool also takes a `database` argument. Characters like `@`, `:` and `/` in the password must be percent-encoded (`%40`, `%3A`, `%2F`). Create a user that can only read: - Atlas: Security → Database & Network Access → Database Users → Add New Database User, Password authentication, built-in role "Only read any database" (or the `read` role on just the databases Cogny should see, under Specific Privileges). - Self-hosted: `db.createUser({user: "cogny_reader", pwd: "", roles: [{role: "read", db: ""}]})`. `get_server_info` lists the user's roles and warns when one of them can write. Every Cogny connection comes from `207.175.17.47`. On Atlas, add it under Database & Network Access → IP Access List; on your own server, allow it in the firewall. The server must be reachable from the internet and use TLS with a certificate from a public certificate authority (Atlas does by default). Filters, projections, sorts and pipelines are JSON in MongoDB Extended JSON, so an ObjectId is `{"$oid": "…"}` and a date is `{"$date": "2026-10-01T00:00:00Z"}`. `describe_collection` infers the fields from a random sample of up to 500 documents: a field that only a few documents have may not show up. Every operation stops after 60 seconds. `find_documents` returns up to 1,000 documents per call (50 by default), `run_aggregation` up to 2,000 rows (200 by default) and `get_distinct_values` up to 5,000 values, and each says when a result was cut. Large documents are shortened: long strings, long arrays and deep nesting are trimmed, and a response stops at about 500,000 characters. Aggregate with `run_aggregation` rather than paging through raw documents. ## Known gaps - Read only. No tools insert, update or delete documents, or create collections, indexes or users. - `$out` and `$merge` (which write), `$where`, `$function` and `$accumulator` (server-side JavaScript) and `$changeStream` are refused. - Only username/password (SCRAM) users. X.509 certificates, AWS IAM, OIDC/workload identity and Kerberos/LDAP logins can't be connected. - Connection-string options that turn off certificate checks, point at local certificate files or route through a proxy are refused, and so is `tls=false`. - A MongoDB reachable only inside a private network (VPC peering, Private Endpoint, PrivateLink) can't be connected. - No Atlas administration: clusters, backups, alerts, Atlas Search index management and the Atlas Data API are not covered. - No change streams or live updates; each call reads the data as it is at that moment. ## All tools | Tool | Kind | What it does | |---|---|---| | `get_server_info` | Read | Check the MongoDB connection: the database user, its roles, the server version and whether the user could write. | | `list_databases` | Read | List the databases the connected user can read, with their size on disk. | | `list_collections` | Read | List the collections and views in a database, with approximate document counts. | | `describe_collection` | Read | Show a collection's fields and their types (inferred from a random sample), its indexes, document count and a few example documents. | | `find_documents` | Read | Find documents in a collection with a filter, projection and sort. | | `count_documents` | Read | Count the documents in a collection that match a filter. | | `run_aggregation` | Read | Run a read-only aggregation pipeline on a collection and return the result rows. | | `get_distinct_values` | Read | List the distinct values of one field in a collection, optionally within a filter. | Exact input schemas come from `tools/list` once MongoDB is connected; the free plan is enough to check. Missing something? Your agent can ask for it with `request_feature`. --- All integrations: https://cogny.com/integrations/tools/index.md Plans, approvals, limits and data protection: https://cogny.com/buying-guide.md What Cogny is: https://cogny.com/llms.txt