# start_trace

Start an Unreal Insights trace session with selected channels.

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

## Facts

- Tool: `start_trace`
- 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: Execute (High risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 1
- Recommended policy verdict: Rate-limited

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `channels` | array | no | Trace channels: cpu, gpu, frame, memory, counters, bookmark, file, net, loadtime |

Parameters from the server's own tool schema.

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

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

## Why start_trace is rated High

This tool executes a profiling/tracing operation in Unreal Engine, which is an external system action. While not destructive or permanently modifying data, trace sessions consume resources and affect system state during their execution. The action is triggered by the tool call and its effects depend on parameters (selected channels).

From the tool's own definition: "Tool name is 'start_trace' and description states it 'Start[s] an Unreal Insights trace session with selected channels.' Starting a trace session triggers external profiling/monitoring operations whose runtime behavior and resource consumption depend on…"

## Use case

AI agents invoke start_trace to trigger actions in Unreal. 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 Unreal:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "start_trace": {
      "limits": [
        {
          "counter": "start_trace_rate",
          "window": "minute",
          "max": 10,
          "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