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

Annotations already declare readOnlyHint=true, and the description adds value by stating 'Always free' and clarifying that the tool returns per-tool pricing/allowance information for metered tools below. This goes beyond the annotation without contradicting it, effectively communicating the non-destructive, no-cost nature of the operation.

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 a single, information-dense sentence that front-loads the primary action and resource ('Browse stock screens by category') before listing the categories and output contents. It is efficient and clearly structured, though the long list of categories makes it slightly dense. No redundant or filler phrases are present.

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 presence of an output schema, the description does not need to detail return values. It adequately explains the tool's purpose, the types of screens included, what each entry contains, and its role as a starting point for obtaining screen ids. It could mention that category_id is optional (though the schema does), but overall it is sufficient for a discovery/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?

The input schema covers the only parameter (category_id) at 100% with a clear description. The tool description mentions the category list in prose but does not add any new semantic detail about the parameter itself (e.g., valid formats or interaction with the category list). Since schema coverage is high, 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 states a specific verb ('Browse') and resource ('stock screens'), enumerates the categories, and specifies exactly what each entry contains (display names, descriptions, member counts, pricing). It also signals its role as the entry point for finding a screen id, clearly distinguishing it from more specific sibling tools like get_smart_list that retrieve a single screen's details.

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 gives usage context ('Start here to find a screen id') and notes that the tool is free, implying it is a safe discovery step. However, it does not explicitly name alternative tools or conditions under which one should use a sibling (e.g., use get_smart_list for a known screen). The guidance is implied rather than explicit.

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