Start an Unreal Insights trace session to capture performance data from selected channels like CPU, GPU, and frame. Use it to diagnose and analyze Unreal Engine performance issues.
Start an Unreal Insights trace session with selected channels.
| Name | Required | Description | Default |
|---|---|---|---|
| channels | No | Trace channels: cpu, gpu, frame, memory, counters, bookmark, file, net, loadtime |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must disclose behavior. It only states that it starts a trace session, but does not mention side effects, resets, or whether prior traces are stopped, or any performance impact. The description implies a state change (starting a session) but lacks detail on session lifecycle or resource usage.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
It is a single concise sentence that is front-loaded with the action. No fluff, but could be slightly more informative with a hint about usage.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool that likely requires a running environment (e.g., Editor), the description lacks important context like whether it requires a connection, how to verify success, or what happens to existing traces. No output schema, so the description should explain return or failure modes, but it does not.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema already has 100% coverage with a description of each channel and a default value. The description's mention of 'selected channels' adds minimal value, but the schema is sufficient. Baseline 3 is appropriate because the schema does the heavy lifting.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the verb 'Start' and the resource 'Unreal Insights trace session', specifying that channels are selected. It distinguishes from the sibling 'stop_trace' by implying a start action, though it does not explicitly differentiate from other tracing-related tools like 'start_csv_profiling'.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance on when to use this tool versus alternatives, such as CSV profiling or other trace tools. The description does not mention prerequisites (e.g., connection status, running editor) or when not to use it, leaving the agent to infer usage from the name and siblings.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.