# 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-go/black

## Facts

- Tool: `black`
- Server: Go (`Dave-London/Pare`) — https://policylayer.com/tools/io-github-dave-london-go.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

The tool executes the Black formatter on code files, which actively modifies file contents on disk. Since it can reformat (overwrite) files, it has side effects beyond just reading. It's not purely destructive (files aren't deleted, and formatting is reversible with version control), but it does execute an external process that modifies files, making Execute the appropriate category.

From the tool's own definition: "Runs Black code formatter and returns structured results (files changed, unchanged, would reformat)"

## Use case

AI agents invoke black to trigger actions in Go. 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 Go:

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

## Other tools on Go (201)

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