device_list

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

No annotations are supplied, so the description carries the full burden and does: it declares read-only with zero side effects ('changes nothing'), discloses platform limits (macOS only, physical iPhones unsupported), and enumerates the prerequisite states it surfaces (USB debugging, authorization, idb). It also implies the return content — device list plus required setup steps — which compensates for the missing output schema.

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, front-loaded with the resource list and the most actionable constraint (read-only) early. The first sentence is dense with parenthetical platform notes, but every clause carries information an agent needs; nothing reads as 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?

For a zero-parameter, no-output-schema discovery tool, the description covers what is returned (connected devices and their required setup steps), what is not covered (physical iPhones), and what to do on an empty result. Only the concrete shape of the response is left implicit.

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?

The tool takes zero parameters, so there is nothing to disambiguate and the baseline of 4 applies. The description adds no parameter detail because none exists.

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 (lists) and precise resource scope: connected Android emulators/USB phones via adb and booted iOS Simulators on macOS, plus a readiness report. An agent can distinguish this discovery tool from action siblings like click_screen or auto_test without opening any 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?

Implies the discovery/前置-context role before driving a device and gives explicit fallback behavior when nothing is connected (tell the user, ask them to check the app). It names a hard exclusion (physical iPhones cannot be driven) but never explicitly routes to a sibling such as use_target or auto_test as the next step.

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