Get distinct values for a field in a collection
AI agents call distinct to retrieve information from MongoDB MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The distinct operation queries a MongoDB collection to return unique values for a specified field. This is a read-only operation with no side effects—it does not create, modify, delete, or execute code. While the MongoDB server as a whole includes destructive tools (deleteMany, deleteOne, dropCollection) and write operations (insertMany, insertOne), the distinct tool itself is purely informational.
From the tool's definition Tool name 'distinct' and description 'Get distinct values for a field in a collection' indicates a query operation that retrieves data without modification or deletion.
Attacks that exploit this kind of access
Get distinct values for a field in a collection. It is categorised as a Read tool in the MongoDB MCP Server MCP Server, which means it retrieves data without modifying state.
Register the MongoDB MCP Server MCP server in PolicyLayer and add a rule for distinct: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches MongoDB MCP Server. Nothing to install.
distinct is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the distinct rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for distinct. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
distinct is provided by the MongoDB MCP Server MCP server (ryaker/mongodb-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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