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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavior beyond that: the returned value depends on whether ios_set_location is active, and reading requires no automation session. It doesn't cover failure modes (e.g. location services disabled), so it is not a 5.

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, zero filler, and the core action is front-loaded before the conditional return-value detail. Every sentence carries information an agent needs.

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 does partially describe the return (simulated value vs real CoreLocation fix), which is the key ambiguity for this tool. It omits the actual payload shape (coordinates, accuracy, timestamp), leaving a minor gap for a simple single-parameter read tool.

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?

There is a single parameter (udid) with 100% schema description coverage, so the schema already documents it fully. The description adds no meaning about the parameter (e.g. whether it accepts a booted simulator UDID or a real device UDID), which is the expected baseline of 3 when 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 states a specific verb and resource ('Read the iOS device's current GPS location') and explicitly distinguishes this tool's behavior from the sibling ios_set_location, so an agent can separate it from ios_clear_location, ios_play_location_route and device_get_location without opening a 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 a clear operating condition: the simulated value is returned when ios_set_location is active and no automation session is required to read it. That is useful context, but it never states when to prefer this tool over alternatives such as ios_play_location_route or the Android/device equivalents, so it stops short of full when/when-not guidance.

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