flake-check
Checks a Nix flake for errors and returns structured check results, warnings, and errors.
This record as markdown: /tools/io-github-dave-london-go/flake-check.md
What flake-check does on Go
AI agents call flake-check to retrieve information from Go without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why flake-check is rated Low
The tool is read-only: it checks and validates Nix flake files and returns diagnostic output without altering state, executing external commands, or triggering deployments. The highest risk is if malformed input causes a crash, but this is operational risk, not capability risk.
From the tool's definition Tool performs 'Checks a Nix flake for errors and returns structured check results, warnings, and errors' — this is a validation/analysis operation with no side effects. It reads and inspects flake configuration but does not modify, execute, or delete anything.
Attacks that exploit this kind of access
The rule that runs flake-check safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Go, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For flake-check, this is the rule to start with:
flake-check is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Go, apply this rule, and every flake-check call is checked against it from then on.
Questions about flake-check
Checks a Nix flake for errors and returns structured check results, warnings, and errors. It is categorised as a Read tool in the Go MCP Server, which means it retrieves data without modifying state.
Register the Go MCP server in PolicyLayer and add a rule for flake-check: 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 Go. Nothing to install.
flake-check is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the flake-check 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 flake-check. 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.
flake-check is provided by the Go MCP server (Dave-London/Pare). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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