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

With no annotations, the description carries the full behavioral burden. It discloses that playback is asynchronous, returns immediately, advances through waypoints in order, persists the simulated location until ios_clear_location is called, and applies only to iOS 17+. This is strong behavioral disclosure.

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 sentences, each earning its place: purpose and differentiation, input options, and async/stopping behavior. The key differentiator is front-loaded and the structure is clean.

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?

For a tool with no output schema and no annotations, the description covers the essential runtime behavior: how playback works, the two mutually exclusive input modes, return timing, polling progress, stopping, persistence, and the iOS version requirement. No critical calling information 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?

Schema coverage is 100%, so the baseline is 3. The description adds minimal semantics beyond the schema: it explains the 'pace' meaning of secondsPerLeg and that gpxPath is server-side, but these largely restate what the schema already documents.

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 clearly states the tool replays a moving GPS route on an iOS device, contrasting it with a teleport. This distinguishes it from related location tools like ios_set_location and route-focused 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?

The description explains when to use it (continuous movement instead of a single teleport) and names the follow-up tools ios_get_location and ios_clear_location. It does not explicitly name alternative tools like ios_set_location or state when not to use it, but the context is clear enough for correct selection.

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