List available iOS simulators

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

With no annotations, the description carries the behavioral burden. It conveys a read-only enumeration action ('List') and implies UDIDs are available in the result, but it does not state the return format, whether unavailable devices are included, or explicitly confirm it has no side effects. The core behavior is clear but minimally elaborated.

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 short sentences with no filler. The first states the action and mechanism; the second states when to call it. Every sentence earns its place.

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 read-only list tool with no output schema, the description is largely complete: it provides the action, mechanism, and timing relative to action-oriented siblings. A minor gap is the lack of an explicit note about the exact output shape, but the UDID usage hint partially covers that.

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 has zero parameters, so no parameter documentation is needed and the baseline is 4. The description adds no parameter details, but none are required for correct invocation.

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 ('List') and resource ('available Simulator devices') and adds the implementation mechanism 'xcrun simctl'. The second sentence distinguishes it from booting, installing, launching, and screenshot tools by positioning it as the prerequisite lookup when the UDID is unknown.

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 explicitly says to use the tool 'before booting, installing, launching, or capturing screenshots when you do not know the simulator UDID', which is clear when-to-use context. It does not name alternative tools or explicitly state when not to use it, so it stops short of full routing guidance.

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