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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), so the bar is lower. The description adds real behavioral context beyond that: results are sorted by 'featured' by default, and critically that the coupon code is not returned directly but is revealed via the coupon `url` on the site.

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 tight sentences with no filler. Scope is front-loaded, sort behavior follows, and the code-revelation caveat is the last and most actionable detail. Every sentence earns its place.

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 read-only list tool with full schema coverage and no output schema, the description covers the essentials, including the non-obvious fact that codes come from the URL rather than the payload. Pagination (limit/offset) is left entirely to the schema, which is acceptable at 100% coverage.

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 description coverage is 100%, so the baseline is 3. The description largely restates what the schema documents (shop, category, type, sort) and adds only marginal nuance, notably that 'featured' means 'exclusive and top first' — useful but not enough to exceed the baseline.

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+resource ('Live coupons and offers on this site') with scope ('across shops or filtered by shop, category or kind'). The sibling set (get_shop, list_categories, list_events, search_shops, site_info) is clearly distinct in domain, so no explicit sibling routing is needed, but the description also does not name one.

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 implies usage by describing the filtering and sorting modes ('filtered by shop, category or kind', sort options), but never says when to prefer this over a sibling like search_shops or list_categories, nor any when-not condition. Usage is inferable rather than stated.

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