# 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-docker/flake-check

## Facts

- Tool: `flake-check`
- Server: Docker (`@paretools/docker`) — https://policylayer.com/tools/io-github-dave-london-docker.md
- Install: `npx -y @paretools/docker`
- 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

flake-check is a read-only diagnostic tool that analyzes Nix flake configurations and reports results. It has no side effects, does not execute arbitrary code, does not modify data, and does not delete or create resources. The operation is purely informational - checking for errors and returning structured results. This aligns with the Read category of retrieves or queries data with no side effects.

From the tool's own definition: "Tool performs 'Checks a Nix flake for errors and returns structured check results, warnings, and errors' - this is a validation/inspection operation that retrieves diagnostic information without modifying any data."

## Use case

AI agents call flake-check to retrieve information from Docker 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 Docker:

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

## Other tools on Docker (201)

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