Get detailed information about a specific tool, including its arguments and constraints.
AI agents call gateway.describe to retrieve information from PMCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and returns information about tool schemas, arguments, and constraints. It performs a query operation with no ability to modify, execute, or delete data. The action is purely informational and read-only, making it low severity even in a gateway context where it could inform subsequent tool selection.
From the tool's definition Tool name 'describe' and description 'Get detailed information about a specific tool' indicate retrieval of metadata with no side effects.
Documented attack patterns abuse exactly the kind of access gateway.describe gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and PMCP, and nothing reaches the server without passing your rules. This is the rule we recommend for gateway.describe:
{
"version": "1",
"default": "deny",
"tools": {
"gateway.describe": {}
}
}gateway.describe is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get detailed information about a specific tool, including its arguments and constraints. It is categorised as a Read tool in the PMCP MCP Server, which means it retrieves data without modifying state.
Register the P MCP server in PolicyLayer and add a rule for gateway.describe: 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 PMCP. Nothing to install.
gateway.describe 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 gateway.describe 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 gateway.describe. 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.
gateway.describe is provided by the P MCP server (viperjuice/pmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from PMCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
26 PMCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.