services_start · Yaver MCP: Risk & Policy

WHAT IT DOES

What services_start does on Yaver

AI agents invoke services_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.

PARAMETERS

Parameter	Type	Required	Description
`names`	array	—	Service names to start (empty = all)

Parameters from the server's own tool schema.

WHY IT NEEDS A POLICY

Why services_start needs a policy

services_start triggers real processes with real consequences. An agent gone sideways doesn't fire it once — it starts dozens of builds, sends mass notifications, or burns through compute before anyone looks up.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

services_start Rate-limited

services_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": {
    "services_start": {
      "limits": [
        {
          "counter": "services_start_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Yaver, so you can run agents against it safely.

FAQ

Questions about services_start

What does the services_start tool do? +

Start all or specific local development services (Postgres, Redis, MinIO, etc.) from .yaver/services.yaml. 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 services_start accept? +

services_start accepts 1 parameter: names. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on services_start? +

Register the Yaver MCP server in PolicyLayer and add a rule for services_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 services_start? +

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

Can I rate-limit services_start? +

Yes. Add a rate_limit block to the services_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 services_start completely? +

Set action: deny in the PolicyLayer policy for services_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 services_start? +

services_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.