Frame profile

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, and the description adds meaningful behavioral context: the live-mode vs headless caveat, the enumeration of cause categories (script, gc, upload, compile, layout, throttled, hidden, unknown) with confidence and hints. It doesn't contradict the annotation. Minor gap: no mention of measurement overhead or duration for what is presumably a longer-running profiling pass.

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?

Front-loaded with the core answer (why the game stutters) followed by the payload shape, then the routing rule. Dense but each sentence carries information; the 'debuff's update and render' span sentence is the only mildly cryptic bit.

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?

With no output schema, the description carries the full burden of describing return values, and it does so: percentiles, hitches per minute, per-hitch cause/confidence/script/function/hint, plus span timing. Combined with the live-mode caveat, an agent has enough to interpret results correctly.

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 tool takes zero parameters, so the baseline is 4. The schema is empty and there is nothing for the description to clarify about inputs.

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?

Names the concrete artifact it produces (frame-time p50/p95/p99, hitches per minute, worst hitches with causes and confidence) and explicitly contrasts itself with the game_frames sibling. An agent can tell exactly what this tool returns without reading anything else.

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?

States the selection rule directly: 'Prefer this over game_frames to explain stutter,' and adds a prerequisite constraint ('measure in live mode, since headless stepping doesn't reflect real play'). Both the alternative and the when-not condition are explicit.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.