List devices and output sizes

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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering the safety profile. The description adds useful context by enumerating the exact device frames and output targets it surfaces, but says nothing about ordering, pagination, or format beyond those values.

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?

A single front-loaded sentence with zero filler. Every token—verb, resources, and concrete enumerated values—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 no-parameter, no-output-schema list tool whose annotations carry the safety profile, the description is largely complete; the enumerated values effectively preview the return content. It could be stronger by noting that returned values feed generate_screenshots, but nothing essential 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?

The tool takes zero parameters, so the baseline is 4. There is no parameter behavior for the description to clarify, and the schema/annotations already cover the empty input contract.

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 ('List') and precise resources ('device frames' and 'store output targets'), then enumerates concrete values (iphone, iphone-duo, android, ipad; ios-6.9 1320x2868, etc.). This makes it immediately distinguishable from list_styles and the other siblings 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?

Usage is implied rather than stated: the enumeration of valid device frames and output targets signals this is a discovery tool to consult before calling generate_screenshots. However, there is no explicit when-to-use instruction, no named alternative, and no exclusions.

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