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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, and the description repeats 'Read-only.' It adds valuable behavioral context: the store-specific device types ('The App Store gets Apple devices only; Google Play gets Android phones') and the fact that it returns defaults used by create_project. This goes beyond the annotation safety profile.

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 two sentences, front-loaded with the main action and scope, and contains no filler. Each clause adds distinct information: what is listed, for which store, the defaults relationship, store-specific device behavior, and read-only safety. It is efficient and well-structured.

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 simple list tool with a single optional parameter, the description fully covers what it returns (frames, colors, canvas sizes, defaults), how the parameter affects output (device types per store), and safety (read-only). No output schema is needed since the contents are explicitly named. The description is complete for an agent to call it correctly.

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 schema covers 100% of parameters and describes 'store' as 'Which store the screenshots are for.' The description enriches this by explaining the effect of each enum value: App Store → Apple devices, Play → Android phones. This helps the agent choose the correct store value without opening the schema or guessing.

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 ('Lists'), the resource ('device frames, frame colours and canvas sizes'), and the scope ('for one store'). It also ties to a sibling tool ('create_project') by mentioning the defaults it uses, which clearly differentiates this read-only list tool from the create/finish/get 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 implicitly conveys when to use it: when you need to know available frames/colors/canvas sizes and the defaults for create_project. It doesn't explicitly name alternatives or exclusion conditions, but the context of the sibling tools (create_project, finish_project, get_workflow) makes the use case clear without being stated.

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