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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds substantive context by enumerating what the response contains, which matters because there is no output schema; only error behavior for an invalid slug is left unstated.

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 sentences, zero waste. The payload description comes first and the usage routing second, which is the right order for an agent scanning the definition.

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?

With no output schema, naming the returned fields is exactly the right compensation, and the single required parameter is fully documented elsewhere. Minor gap: no mention of what happens when a slug is unknown or not found.

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?

Schema coverage is 100% and the slug parameter's description already names its source (list_templates) and gives an example (violet-beauty). The description adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 and resource ('Get one AppScreenshoot screenshot template in detail') and enumerates the content returned: screen sequence, headline/subtitle copy, preview images, canvas size, and editor link. This clearly separates it from the sibling list_templates, which is a listing operation.

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?

Explicitly prescribes the workflow: 'Use this after list_templates to inspect or recommend a specific design,' which tells the agent when to call it and in what order. It stops short of stating when-not to use it (e.g., what to do if only a summary is needed), so it falls just below top marks.

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