Register an externally-discovered MCP server package so it can be provisioned.
AI agents use gateway.register_discovered_server to create or update resources in PMCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your PMCP environment.
This tool creates a new registry entry for an MCP server package, which is a reversible write operation. It does not execute code directly, but it enables future provisioning of servers. Misuse could allow an attacker to register malicious server packages, hence medium severity.
From the tool's definition Register an externally-discovered MCP server package so it can be provisioned
Documented attack patterns abuse exactly the kind of access gateway.register_discovered_server 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.register_discovered_server:
{
"version": "1",
"default": "deny",
"tools": {
"gateway.register_discovered_server": {
"limits": [
{
"counter": "gateway.register_discovered_server_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}gateway.register_discovered_server stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Register an externally-discovered MCP server package so it can be provisioned. It is categorised as a Write tool in the PMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the P MCP server in PolicyLayer and add a rule for gateway.register_discovered_server: 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.register_discovered_server is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the gateway.register_discovered_server 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.register_discovered_server. 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.register_discovered_server 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.