Measure frame timing

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

No annotations exist, so the description carries the full burden. It does disclose a genuinely important behavioral trait: results are platform-dependent, with real UI-thread frames only on Android/dumpsys gfxinfo and physical iOS devices via xctrace, while the iOS simulator yields only JS-thread rAF rate. It omits whether a device/app must be connected first, what the returned metrics look like, and any cost or blocking behavior of the 'short window'.

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?

Two sentences, front-loaded with the core action, and the platform caveat follows efficiently. Slight vagueness in 'short window' rather than a concrete default keeps it from being maximally crisp.

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 annotations, no output schema, and zero schema description coverage on three parameters, the description should compensate but doesn't. It covers platform data-quality caveats well yet leaves the agent without guidance on required setup (connected device, running app) or what the measurement returns.

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?

Schema description coverage is 0% for three parameters (app_id, device, duration_ms), and the description never explains any of them. 'Short window' loosely gestures at duration_ms but gives no units or default, and app_id/device semantics (target selection, whether device is required) are entirely undocumented.

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?

States a specific verb and resource ('Measure frame timing for a short window'), which is clear on its own. It doesn't name which sibling to prefer over it (profile_renders, profile_js, sample_cpu all sound related to performance measurement), so an agent must infer differentiation from the names alone.

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?

The description implies a measurement use case but never says when to pick this over profile_renders, profile_js, or sample_cpu. The platform caveats tell the agent what data is trustworthy on Android vs the iOS simulator, which is useful context but not a when-to-use rule.

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