expose_start

Expose a local port to the internet. Replaces ngrok ($10/mo). Uses Cloudflare Quick Tunnel (free, zero config).

SERVERYaver SOURCEyaver-cli

High RISK CLASS

Category Execute

Parameters 21 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-kivanccakmak-yaver/expose-start.md

WHAT IT DOES

What expose_start does on Yaver

AI agents invoke expose_start 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	Yes	Local port to expose
`subdomain`	string	—	Preferred subdomain (best-effort)

Parameters from the server's own tool schema.

RISK

Why expose_start is rated High

This tool executes a network tunnel operation that activates external infrastructure (Cloudflare Quick Tunnel) and creates side effects (public internet exposure of a local service). While not directly destructive or financial, it is an Execute action because it triggers an external operation whose consequences depend on arguments.

From the tool's definition Tool exposes a local port to the internet and explicitly replaces ngrok. The action of 'expose' combined with internet accessibility is a network operation that triggers external infrastructure changes and creates a public endpoint whose effects depend on…

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs expose_start 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_start, this is the rule to start with:

expose_start Rate-limited

expose_start 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "expose_start": {
      "limits": [
        {
          "counter": "expose_start_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Yaver, apply this rule, and every expose_start call is checked against it from then on.

FAQ

Questions about expose_start

What does the expose_start tool do? +

Expose a local port to the internet. Replaces ngrok ($10/mo). Uses Cloudflare Quick Tunnel (free, zero config). 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.

What parameters does expose_start accept? +

expose_start accepts 2 parameters: port, subdomain. Required: port. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on expose_start? +

Register the Yaver MCP server in PolicyLayer and add a rule for expose_start: 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.

What risk level is expose_start? +

expose_start is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit expose_start? +

Yes. Add a rate_limit block to the expose_start 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.

How do I block expose_start completely? +

Set action: deny in the PolicyLayer policy for expose_start. 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.

What MCP server provides expose_start? +

expose_start 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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