# flake-check

Checks a Nix flake for errors and returns structured check results, warnings, and errors.

Agent View of the PolicyLayer registry record for `flake-check`. HTML page: https://policylayer.com/tools/io-github-dave-london-npm/flake-check

## Facts

- Tool: `flake-check`
- Server: Npm (`Dave-London/Pare`) — https://policylayer.com/tools/io-github-dave-london-npm.md
- Homepage: https://github.com/Dave-London/pare
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "flake-check",
    "arguments": {}
  }
}
```

## Why flake-check is rated Low

The tool performs static analysis/validation of Nix flake files, returning diagnostic information. It has no side effects, does not modify files, does not execute code, and does not move data or delete anything. This is a purely informational read operation with minimal blast radius if misused by an AI agent.

From the tool's own definition: "Tool description states it 'Checks a Nix flake for errors and returns structured check results, warnings, and errors' - a read-only operation that validates and inspects configuration without modifying or executing anything."

## Use case

AI agents call flake-check to retrieve information from Npm without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Npm:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "flake-check": {}
  }
}
```

## Other tools on Npm (201)

- `branch` — Destructive — https://policylayer.com/tools/io-github-dave-london-npm/branch.md
- `clean` — Destructive — https://policylayer.com/tools/io-github-dave-london-npm/clean.md
- `package-clean` — Destructive — https://policylayer.com/tools/io-github-dave-london-npm/package-clean.md
- `remove` — Destructive — https://policylayer.com/tools/io-github-dave-london-npm/remove.md
- `reset` — Destructive — https://policylayer.com/tools/io-github-dave-london-npm/reset.md
- `secret-delete` — Destructive — https://policylayer.com/tools/io-github-dave-london-npm/secret-delete.md
- `tag` — Destructive — https://policylayer.com/tools/io-github-dave-london-npm/tag.md
- `variable-delete` — Destructive — https://policylayer.com/tools/io-github-dave-london-npm/variable-delete.md
- `workspace` — Destructive — https://policylayer.com/tools/io-github-dave-london-npm/workspace.md
- `worktree` — Destructive — https://policylayer.com/tools/io-github-dave-london-npm/worktree.md
- `add` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/add.md
- `add-package` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/add-package.md
- `ansible-galaxy` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/ansible-galaxy.md
- `ansible-playbook` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/ansible-playbook.md
- `api` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/api.md
- `apply` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/apply.md
- `bazel` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/bazel.md
- `biome-check` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/biome-check.md
- `bisect` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/bisect.md
- `black` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/black.md
- `build` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/build.md
- `bundle-exec` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/bundle-exec.md
- `bundle-install` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/bundle-install.md
- `check` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/check.md
- `checkout` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/checkout.md
- `cherry-pick` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/cherry-pick.md
- `clippy` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/clippy.md
- `cmake` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/cmake.md
- `compose-build` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/compose-build.md
- `compose-down` — Execute — https://policylayer.com/tools/io-github-dave-london-npm/compose-down.md
- …and 171 more: https://policylayer.com/tools/io-github-dave-london-npm.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=io-github-dave-london-npm · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-github-dave-london-npm