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MongoDB MCP Server Configuration Options

The MCP Server has various options that you can set to connect to a MongoDB cluster and control MCP Server operations. You can set the options in a JSON configuration file, through a command line, or using operating system environment variables.

Options List

Use the following configuration options to configure the MCP Server.

Important

If you're a MongoDB Enterprise or MongoDB Atlas user and you require a specific authentication mechanism, see the MongoDB MCP Server Security section to learn about the configuration options for your authentication method.

CLI Option Name	OS Environment Variable Name	Type	Default	Description
`apiClientId`	`MDB_MCP_API_CLIENT_ID`	string	Not set	Atlas API client ID for authentication.
`apiClientSecret`	`MDB_MCP_API_CLIENT_SECRET`	string	Not set	Atlas API client secret for authentication.
`connectionString`	`MDB_MCP_CONNECTION_STRING`	string	Not set	Connection string for a direct database connection. Sets the connection string at runtime to allow the client to directly connect to a cluster. Important The `--connectionString` CLI argument is deprecated. Use the `MDB_MCP_CONNECTION_STRING` environment variable instead. If environment variables are not an option, use the first positional argument. Note Typically, avoid providing the connection string at runtime because you expose the connection credentials to the large language model. The connection string is used if the client has never connected before, or the client switches the connection to a new cluster if the client was previously connected. After the client calls the connect or switch connection tool, the client reuses the same connection for subsequent operations. Therefore, you only need to call the connect or switch connection tool once or if you need to switch to a different connection.
`dryRun`	`MDB_MCP_DRY_RUN`	boolean	`false`	Use the dry-run option to examine your MCP Server configuration. When you enable the dry-run option, the MCP Server returns the MCP Server configuration settings and the list of enabled MongoDB MCP Server Tools. To enable the dry-run option, set `--dryRun` in the configuration file or command line, or set the `MDB_MCP_DRY_RUN` operating system environment variable to `true`. For more information, see Enabling MCP Server Dry-Run Mode.
`loggers`	`MDB_MCP_LOGGERS`	string	`disk mcp`	Specifies where the MCP Server sends the logs. Set `loggers` to one or more of the following options: `disk`, which writes logs to disk files located in the path specified in the `logPath` option. `mcp`, which sends the logs to the AI client, if the client supports logging and transport protocol. `stderr`, which sends the logs to the standard error output. This setting is useful for debugging or when running MCP in a container. For example, to set `loggers` to `mcp` and `stderr` in the AI client JSON configuration file or the operating system command line, use `--loggers mcp stderr`. To set the `MDB_MCP_LOGGERS` operating system environment variable to `disk` and `stderr`, use `export MDB_MCP_LOGGERS="disk,stderr"`. For more information about the logging options, see Troubleshoot MongoDB MCP Server.
`logPath`	`MDB_MCP_LOG_PATH`	string	Depends on the operating system	Directory that stores the MCP Server logs. For more information about the log path and operating system specifics, see Troubleshoot MongoDB MCP Server.
`disabledTools`	`MDB_MCP_DISABLED_TOOLS`	array	Not set	An array of MCP tool names, operation types, or tool categories to disable. For more information, see Disabling MCP Server Tools.
`readOnly`	`MDB_MCP_READ_ONLY`	boolean	`false`	To disable cluster write operations, set `--readOnly` in the configuration file or command line, or set the `MDB_MCP_READ_ONLY` operating system environment variable to `true`. Default is to allow cluster write operations. Typically, always enable read-only mode. For more information, see Enabling MCP Server Read-Only Mode.
`indexCheck`	`MDB_MCP_INDEX_CHECK`	boolean	`false`	If `true`, enforces that query operations must use an index and rejects queries that perform collection scans. For more information, see Enabling Index Check.
`telemetry`	`MDB_MCP_TELEMETRY`	string	`enabled`	If `disabled`, MCP Server usage data collection is stopped. For more information, see Disabling MCP Server Telemetry.
`transport`	`MDB_MCP_TRANSPORT`	string	`stdio`	Transport protocol for communications with the MCP Server. Set `transport` to one of the following options: `stdio`, which is the default. Uses the standard input and output for communications with the MCP Server. `stdio` is suitable for most AI clients. `http`, which enables HTTP communications with the MCP Server. You can then use HTTP to interact with the MCP Server from a Web client or communicate with the MCP Server on a specific HTTP IP port. Warning HTTP transport is NOT recommended for production use without implementing proper authentication and security measures.
`httpPort`	`MDB_MCP_HTTP_PORT`	integer	`3000`	IP port number for HTTP communications with the MCP Server.
`httpHost`	`MDB_MCP_HTTP_HOST`	string	`127.0.0.1`	IP address for HTTP communications with the MCP Server. With Streamable HTTP, the MCP Server is bound to `localhost (127.0.0.1)` by default. This ensures the MCP Server only accepts connections that originate on the same computer. Warning Binding to `0.0.0.0` exposes the MCP Server to the entire local network, which allows other devices on the same network to potentially access the MCP Server. This is a security risk and could allow unauthorized access to your database context. If you must expose the MCP Server outside of `localhost`, implement strong security authentication. To learn more, see Remote Connections.
`idleTimeoutMs`	`MDB_MCP_IDLE_TIMEOUT_MS`	integer	`600000`	Idle timeout for a client to disconnect. Only applies to HTTP transport.
`notificationTimeoutMs`	`MDB_MCP_NOTIFICATION_TIMEOUT_MS`	integer	`540000`	Notification timeout for a client to be aware of disconnect. Only applies to HTTP transport.
`authenticationMechanism`	`MDB_MCP_AUTHENTICATION_MECHANISM`	string	`SCRAM-SHA-256`	SCRAM is the default authentication mechanism for MongoDB. To connect to your MongoDB deployments with the MongoDB MCP server using other authentication methods, see the following pages: Connect with OpenID Connect (OIDC) Connect with LDAP Connect with Kerberos Connect with X.509 Certificates Connect with Proxy
`exportsPath`	`MDB_MCP_EXPORTS_PATH`	string	Depends on the operating system	Directory that stores exported data files. For more information about the export path and operating system specifics, see Export Data from MongoDB MCP Server.
`exportTimeoutMs`	`MDB_MCP_EXPORT_TIMEOUT_MS`	integer	`300000`	Time in milliseconds after which exported data files are eligible for deletion by the MCP Server cleanup process.
`exportCleanupIntervalMs`	`MDB_MCP_EXPORT_CLEANUP_INTERVAL_MS`	integer	`120000`	Time period in milliseconds between automatic executions of the MCP Server cleanup process that deletes expired export data files. The cleanup process is run automatically.
`previewFeatures`	`MDB_MCP_PREVIEW_FEATURES`	string	Not set	Comma separated values of preview features that are enabled. Valid values: `search`.

Vector Search Options

Vector search support in MCP is available as a preview feature. To enable this feature, set the previewFeatures flag or MDB_MCP_PREVIEW_FEATURES environment variable to search in your MCP configuration. To learn more, see MongoDB MCP Server Configuration Options.

The following options configure the MCP server's behavior when you use it to work with MongoDB Vector Search.

CLI Option Name	OS Environment Variable Name	Type	Default	Description
`voyageApiKey`	`MDB_MCP_VOYAGE_API_KEY`	string	Not set	Voyage AI API key for automatic embedding generation. When you configure this option, the MCP Server automatically generates embeddings for: Documents that you insert with the `insert-many` tool The `queryVector` parameter in `$vectorSearch` aggregation queries The MCP Server also validates that fields with vector search indexes contain valid embedding vectors to prevent breaking vector search indexes. The MongoDB MCP server supports the following Voyage AI models: `voyage-3-large` `voyage-3.5` `voyage-3.5-lite` `voyage-code-3` To learn more about Voyage AI, see the Voyage AI documentation. For additional vector search configuration options, see Vector Search Options.
`disableEmbeddingsValidation`	`MDB_MCP_DISABLE_EMBEDDINGS_VALIDATION`	boolean	`false`	When set to `true`, disables validation of embedding dimensions. By default, the MCP Server validates that fields with vector search indexes contain valid embedding vectors with the correct dimensions to prevent breaking vector search indexes. Enable this option to allow inserting raw values into embeddings fields without validation. Warning Disabling embeddings validation may result in documents with invalid embeddings that cannot be used with vector search indexes.
`vectorSearchDimensions`	`MDB_MCP_VECTOR_SEARCH_DIMENSIONS`	integer	`1024`	Default number of dimensions for vector search embeddings. This value is used when creating vector search indexes and validating embeddings.
`vectorSearchSimilarityFunction`	`MDB_MCP_VECTOR_SEARCH_SIMILARITY_FUNCTION`	string	`euclidean`	Default similarity function for vector search. Set to one of the following values: `euclidean`: Euclidean distance `cosine`: Cosine similarity `dotProduct`: Dot product similarity The MCP server uses this value is as the default when creating vector search indexes unless specified otherwise. To learn more, see How to Index Fields for Vector Search.

Positional Arguments

The MCP Server accepts a positional argument that can be provided without specifying a CLI flag. The first positional argument is interpreted as the connection string for your MongoDB deployment.

As a security best practice, use the MDB_MCP_CONNECTION_STRING environment variable to set the connection string. If environment variables are not an option, use the first positional argument. For example:

"args": [
   "-y",
   "mongodb-mcp-server",
   "mongodb+srv://<user-name>:<password>@<cluster-name>.mongodb.net/",
   "--readOnly"
]

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Options List

Important

Important

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Vector Search Options

Warning

Positional Arguments

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