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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so safety is covered. The description still adds value beyond them: it discloses that only metadata is returned (not layouts) and imposes a plan-level authorization requirement ('Requires an Indie plan (trial counts)'), which annotations cannot express. It stops short of describing ordering or pagination.

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?

Three short sentences, front-loaded with the core action and payload scope, then routing, then the plan prerequisite. Every sentence carries distinct information and none is redundant with the title.

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, the description takes on the return-value burden and does name the four metadata fields returned, plus the plan prerequisite. It leaves ordering/pagination of the list unspecified, which is a minor gap for a simple one-parameter list tool.

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?

There is a single parameter with 100% schema description coverage, and the schema already tells the agent to find product_id via sonar_list_products. The description adds no syntax, format, or sourcing detail beyond that, so the baseline of 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?

The description opens with a specific verb+resource ('List a product's app-store screenshot sets') and immediately scopes the payload ('metadata only: store, device size, locales, studio_url'). It also explicitly distinguishes itself from sonar_get_screenshot_set, so the agent can separate the two sibling list/get tools without opening either 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?

It states the condition that routes to the alternative ('Use sonar_get_screenshot_set for full layouts') and adds a prerequisite ('Requires an Indie plan (trial counts)'). Both when-to-use and the plan constraint are explicit rather than inferred.

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