# black

Runs Black code formatter and returns structured results (files changed, unchanged, would reformat).

Agent View of the PolicyLayer registry record for `black`. HTML page: https://policylayer.com/tools/io-github-dave-london-pare-search/black

## Facts

- Tool: `black`
- Server: Search (`Dave-London/Pare`) — https://policylayer.com/tools/io-github-dave-london-pare-search.md
- Homepage: https://github.com/Dave-London/Pare
- Risk category: Execute (High risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

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

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

## Why black is rated High

This tool runs an external code formatting process that modifies files on disk. While Black reformatting is generally reversible via version control, it does execute an external process and writes changes to files, placing it in the Execute category (which outranks Write). Misuse could reformat large codebases unintentionally.

From the tool's own definition: "'Runs Black code formatter' — actively executes the Black formatter tool on files, producing side effects (reformatting/modifying source files)."

## Use case

AI agents invoke black to trigger actions in Search. 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.

## Recommended policy (PolicyLayer)

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

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "black": {
      "limits": [
        {
          "counter": "black_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Search (201)

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