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

Annotations only cover idempotency/safety; the description adds substantial behavior beyond them: no automation session required, the fallback route if the developer service is unavailable, a held connection on iOS 17+, the conditions that end the effect, and the reply's `transport` field. This is exactly the kind of context annotations cannot carry.

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 scoping constraint, and every sentence carries information. It is dense with parentheticals (iOS 17+ held connection, transport field), which slightly taxes readability but not enough to call it padded.

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 compensates by explaining the reply's `transport` field, and it covers the persistence and scope caveats an agent needs to call and reason about the result correctly. Nothing material is missing for a 3-param 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?

Schema coverage is 100%, so udid, latitude and longitude are already documented with examples. The description adds no syntax or format detail beyond the schema; the only extra field mentioned (`transport`) is a return value, not a parameter, so baseline 3 applies.

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+resource (set the iOS device's GPS location) plus the purpose (testing location-aware apps), and the mechanism distinguishes it from siblings like ios_play_location_route and ios_get_location. An agent can tell exactly what this does without opening the 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?

Explicitly frames the use case (testing location-aware apps) and states the persistence lifetime, naming ios_clear_location as the counterpart. The SCOPE paragraph gives explicit when-it-applies/when-it-does-not boundaries (CoreLocation vs IP-based geolocation, Wi-Fi/cell triangulation, anti-fraud paths).

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