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

With no annotations provided, the description carries the full behavioral burden and handles it thoroughly. It discloses the PREREQ about Location Services permission with exact navigation steps, the side-effect of silent failure (coordinates cached server-side but apps see zero), and the exact scope of what is and isn't affected. This goes well beyond what a typical setter does.

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?

The description is somewhat long but every sentence earns its place: the mechanism, persistence, prerequisite, and scope all add critical operational information that cannot be inferred from the schema or annotations. The PREREQ and SCOPE sections are clearly labeled and front-loaded with the core purpose. Slightly dense but structured well for agent consumption.

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 the tool's complexity (physical device dependency, permission prerequisite, partial effect scope, server-side caching behavior), the description is remarkably complete. It has no output schema and no annotations, so the description fully compensates, covering device requirements, setup prerequisite, persistence semantics, and limitations. This is a well-rounded description for a tool with these operational foot-guns.

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% and all three parameters are already documented with descriptions (udid, latitude, longitude with examples like 37.7749 and -122.4194). The description does not add parameter-specific detail beyond the schema, but the baseline 3 is appropriate since the schema fully covers parameter meaning.

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 exactly what the tool does: sets the iOS device's GPS location for testing location-aware apps, specifying it works on physical devices (iOS 16.4+) via the bundled iOS automation agent's simulated-location route. It clearly distinguishes this from ios_get_location, ios_clear_location, and device_set_location sibling tools by specifying the iOS-specific mechanism and the 'set' verb + resource (GPS location).

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 explicitly states the physical-device prerequisite (iOS 16.4+), the iOS automation agent route, persistence behavior (until reboot or ios_clear_location), and the Scope section clearly delineating what it does and does not affect (CoreLocation vs IP-based/Wi-Fi/cell-tower/anti-fraud paths). It names the sibling tool ios_clear_location as the inverse operation.

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