Connect or start a known downstream MCP server by name.
AI agents invoke gateway.connect_server to trigger actions in PMCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool executes an operation that initiates an external process (downstream MCP server startup/connection). While the server list is known/constrained, the tool still triggers external effects that go beyond simple data retrieval or reversible modification. It is Execute rather than Write because it involves process control and system operations rather than data mutation.
From the tool's definition Tool description states 'Connect or start a known downstream MCP server by name.' The action of starting/connecting a server triggers external operations and process initialization whose effects depend on which server is specified as the argument.
Documented attack patterns abuse exactly the kind of access gateway.connect_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.connect_server:
{
"version": "1",
"default": "deny",
"tools": {
"gateway.connect_server": {
"limits": [
{
"counter": "gateway.connect_server_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}gateway.connect_server stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Connect or start a known downstream MCP server by name. It is categorised as a Execute tool in the PMCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the P MCP server in PolicyLayer and add a rule for gateway.connect_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.connect_server is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the gateway.connect_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.connect_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.connect_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.