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

With no annotations, the description carries the full burden and does so: it discloses the human-in-the-loop requirement (user must tap Share and the iPhone app must be open), the default 45 s wait with a 50 s cap, and the asynchronous fallback path via 'from' or phone_result. An agent knows exactly what the failure and latency profile looks like before calling.

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 action and the user-interaction caveat, then usage condition, then timing/fallback. Sentences are dense and slightly run-on but each carries distinct information with no filler.

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?

Given no output schema and no annotations, the description covers invocation preconditions, timing behavior, and both sync and async return paths. It does not say what the location answer actually contains (coordinates, address, accuracy), a minor remaining gap.

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 coverage is 67%, and the description adds real meaning beyond the schema: wait_seconds' default of 45 and maximum of 50, and the role of 'from' in routing a late answer back to the task. 'why' is left entirely to the schema, which is acceptable.

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 gives a specific verb and resource: 'Ask the user's iPhone where they are', and the parenthetical clarifies the user interaction required (tap Share, app open). It is clearly distinct from phone_ask and phone_photo by naming location as the payload, though it does not explicitly contrast itself with those siblings.

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?

'Only when where they are changes what you do (travel time, a nearby place, the right time zone)' gives a clear use condition and even examples of qualifying situations. It lacks an explicit comparison to alternatives such as phone_ask, preventing a 5.

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