Return distinct values for one field in a collection with an optional filter.
AI agents call distinct to retrieve information from Askdb without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and aggregates existing data from a database collection—specifically, unique values for a single field. It has no side effects (no create, update, delete, or irreversible operations). The optional filter parameter does not change the read-only nature of the operation. The server's sandbox isolation and field-level control further mitigate risks.
From the tool's definition Tool name 'distinct' and description 'Return distinct values for one field in a collection with an optional filter' indicate a read-only query operation that retrieves data without modification.
Documented attack patterns abuse exactly the kind of access distinct gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Askdb, and nothing reaches the server without passing your rules. This is the rule we recommend for distinct:
{
"version": "1",
"default": "deny",
"tools": {
"distinct": {}
}
}distinct is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Return distinct values for one field in a collection with an optional filter. It is categorised as a Read tool in the Askdb MCP Server, which means it retrieves data without modifying state.
Register the Askdb 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 Askdb. 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 Askdb MCP server (mgorabbani/askdb). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Askdb, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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10 Askdb tools catalogued and risk-classified — across an index of 43,000+ MCP servers.