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

Annotations only declare a non-read-only, idempotent, non-destructive request; the description adds the crucial behavior that this is asynchronous, notification-driven, and completes "within seconds once the app is opened." It also clarifies the return payload is a status rather than data, which the annotations cannot convey.

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?

Three short sentences, front-loaded with the action, followed by the user instruction and the return-value caveat. No redundant wording and every sentence carries distinct information.

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 properly covers what comes back ("request status, not health data") and the required user intervention before re-reading. Nothing an agent needs to invoke and follow up correctly is missing.

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 has zero parameters, so there is nothing for the description to disambiguate beyond the empty schema. Baseline applies; the brief mention that no arguments are needed is implicit in the call instructions.

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 uses a specific verb and resource ("Ask the user's iPhone for fresh Apple Health data") and explicitly distinguishes the outcome from the read siblings by stating "Returns request status, not health data." An agent can tell this apart from fetch_health_data or get_daily_metrics without opening any schema.

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?

It gives the full when-and-how: call this tool, tell the user to open P.R.O., then call the read tools again. That names both the trigger condition and the alternative/gating step, leaving no inference about ordering or follow-up.

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