This record as markdown: /tools/io-github-kivanccakmak-yaver/check-single.md
What check_single does on Yaver
AI agents invoke check_single 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 |
|---|---|---|---|
fix | boolean | — | Auto-fix if possible |
name | string | Yes | Check name: git-clean, typecheck, lint, format, tests, build, bundle-size, security-audit, env-vars, deps |
Parameters from the server's own tool schema.
Why check_single is rated High
The tool actively runs/executes a check rather than merely reading static data. Pre-deployment checks commonly involve running scripts, validating configurations, or probing services, which constitutes execution of external operations. It is not destructive or financial, but it does execute logic with potential side effects depending on what the check does.
From the tool's definition 'Run a single pre-deployment check' — the word 'Run' indicates execution of an operation; pre-deployment checks typically invoke scripts, commands, or system probes
Attacks that exploit this kind of access
The rule that runs check_single 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 check_single, this is the rule to start with:
check_single 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 check_single call is checked against it from then on.
Questions about check_single
Run a single pre-deployment check. 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.
check_single accepts 2 parameters: fix, name. Required: name. 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 check_single: 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.
check_single 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 check_single 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 check_single. 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.
check_single 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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