list_export_sizes

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

With no annotations, the description fully covers behavior: it is a read-only listing operation with no side effects. It clearly states the output contains ids, labels, and dimensions for two platforms.

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?

Single, well-structured sentence that front-loads the verb and resource, and includes all essential details without extraneous words.

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?

Given the simplicity (no parameters, no output schema, no nested objects), the description is complete. It explains what the tool lists, for which platforms, and the nature of the data returned.

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?

No parameters exist, and baseline for zero-parameter tools is 4. The schema coverage is 100% trivially, so the description adds no further param information beyond the schema.

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?

Description clearly uses verb 'List' with specific resource 'supported App Store and Play Store screenshot export sizes', and explicitly mentions the data fields (ids, labels, dimensions). It distinguishes from sibling tools like generate_screenshot and list_layouts which have different purposes.

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?

Context is clear: this tool is for enumerating available export sizes before generating screenshots. However, it does not explicitly state when not to use it or provide alternatives, so it scores 4 instead of 5.

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