AI agents call discover_instances to retrieve information from QueryNest without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool discovers and lists available MongoDB instances. It is a read-only enumeration operation with no side effects. Misuse risk is low as it only exposes instance metadata, though it could reveal infrastructure topology to an attacker.
From the tool's definition 发现和列出所有可用的MongoDB实例 — 'discover' and 'list' indicate retrieval only; no modification implied
Attacks that exploit this kind of access
发现和列出所有可用的MongoDB实例. It is categorised as a Read tool in the QueryNest MCP Server, which means it retrieves data without modifying state.
Register the QueryNest MCP server in PolicyLayer and add a rule for discover_instances: 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 QueryNest. Nothing to install.
discover_instances 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 discover_instances 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 discover_instances. 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.
discover_instances is provided by the QueryNest MCP server (niuzaishu/querynest). 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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