This record as markdown: /tools/io-github-kivanccakmak-yaver/expose-stop.md
What expose_stop does on Yaver
AI agents invoke expose_stop to trigger actions in Yaver. 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.
| Parameter | Type | Required | Description |
|---|---|---|---|
port | integer | — | Port to stop (0 = stop all) |
Parameters from the server's own tool schema.
Why expose_stop is rated High
Stopping a tunnel is an Execute action because it triggers an external operation (network tunnel termination) whose effects are immediate and depend on which tunnel the argument specifies. It is not Destructive (data is not deleted/overwritten), not Write (no data creation/modification), and not Financial.
From the tool's definition Tool name 'expose_stop' and description 'Stop a tunnel' indicate termination of an active network tunnel—a runtime operation that triggers immediate external effects (tunnel teardown).
Attacks that exploit this kind of access
The rule that runs expose_stop safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Yaver, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For expose_stop, this is the rule to start with:
expose_stop 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Yaver, apply this rule, and every expose_stop call is checked against it from then on.
Questions about expose_stop
Stop a tunnel. It is categorised as a Execute tool in the Yaver MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
expose_stop accepts 1 parameter: port. The full parameter table on this page comes from the server's own tool schema.
Register the Yaver MCP server in PolicyLayer and add a rule for expose_stop: 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 Yaver. Nothing to install.
expose_stop 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 expose_stop 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 expose_stop. 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.
expose_stop is provided by the Yaver MCP server (yaver-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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