# undo

Undo the last editor action.

Agent View of the PolicyLayer registry record for `undo`. HTML page: https://policylayer.com/tools/jjpxdev-unreal-mcp/undo

## Facts

- Tool: `undo`
- Server: Unreal (`@jjpxdev/unreal-mcp`) — https://policylayer.com/tools/jjpxdev-unreal-mcp.md
- Install: `npx -y @jjpxdev/unreal-mcp`
- Homepage: https://www.npmjs.com/package/@jjpxdev/unreal-mcp
- Risk category: Write (Medium 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": "undo",
    "arguments": {}
  }
}
```

## Why undo is rated Medium

This tool reverts prior Write or Execute operations (e.g., reversing actor creation, blueprint modifications, asset changes) but does not itself delete or permanently destroy data—it restores a previous state. While the action is reversible in nature, it modifies editor state and can affect complex multi-step workflows.

From the tool's own definition: "Tool named 'undo' with description 'Undo the last editor action' indicates reversal of modifications made to Unreal Engine editor state."

## Use case

AI agents use undo to create or update resources in Unreal, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Unreal environment.

## Recommended policy (PolicyLayer)

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

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "undo": {
      "limits": [
        {
          "counter": "undo_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Unreal (126)

- `delete_actor` — Destructive — https://policylayer.com/tools/jjpxdev-unreal-mcp/delete-actor.md
- `delete_asset` — Destructive — https://policylayer.com/tools/jjpxdev-unreal-mcp/delete-asset.md
- `delete_material_expression` — Destructive — https://policylayer.com/tools/jjpxdev-unreal-mcp/delete-material-expression.md
- `remove_graph_node` — Destructive — https://policylayer.com/tools/jjpxdev-unreal-mcp/remove-graph-node.md
- `build_cook_run` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/build-cook-run.md
- `build_graph` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/build-graph.md
- `build_plugin` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/build-plugin.md
- `build_target` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/build-target.md
- `call_preset_function` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/call-preset-function.md
- `clean_project` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/clean-project.md
- `compile_blueprint` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/compile-blueprint.md
- `content_audit` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/content-audit.md
- `cook_content` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/cook-content.md
- `execute_console_command` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/execute-console-command.md
- `execute_python` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/execute-python.md
- `generate_lods` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/generate-lods.md
- `package_project` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/package-project.md
- `recompile_material` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/recompile-material.md
- `reinit_niagara_system` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/reinit-niagara-system.md
- `render_sequence` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/render-sequence.md
- `reset_niagara_system` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/reset-niagara-system.md
- `run_all_automation_tests` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/run-all-automation-tests.md
- `run_automation_test` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/run-automation-test.md
- `run_automation_tests_by_category` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/run-automation-tests-by-category.md
- `run_editor_utility_blueprint` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/run-editor-utility-blueprint.md
- `run_editor_utility_widget` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/run-editor-utility-widget.md
- `run_gauntlet` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/run-gauntlet.md
- `run_map_check` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/run-map-check.md
- `run_stat_command` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/run-stat-command.md
- `spawn_niagara_at_location` — Execute — https://policylayer.com/tools/jjpxdev-unreal-mcp/spawn-niagara-at-location.md
- …and 96 more: https://policylayer.com/tools/jjpxdev-unreal-mcp.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`

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Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=jjpxdev-unreal-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/jjpxdev-unreal-mcp