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

Annotations already declare readOnly, idempotent, non-destructive, and non-open-world, so the safety profile is covered. The description adds real value with 'live' (only active offers) and the return shape ('the store and its single best offer, plus a few alternatives'). It does not say what happens when no offer exists — empty result versus error — which is the main residual gap for a lookup tool.

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 filler. The purpose and input flexibility are front-loaded, and the return behavior is packed into the second sentence rather than spread across preamble.

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 does the necessary work by summarizing the return payload (store, best offer, alternatives). Combined with 100% schema coverage on the single parameter, the definition is nearly self-sufficient; only the no-results behavior and any URL-normalization caveats are unstated.

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 there is a single parameter, so the schema already carries the basic meaning. The description still earns credit by widening accepted input forms beyond the schema's 'store or product URL, or a domain' — explicitly naming checkout pages and giving a concrete example URL.

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 — 'find the best live coupon code or deal' — and pins the scope to 'any store or product link ... or bare domain'. The singular 'best offer plus a few alternatives' implicitly separates it from siblings like get_store_offers and get_offer, which read as more targeted lookups.

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?

Guidance is about input acceptability (store URL, product URL, bare domain, checkout pages) rather than about when to pick this tool over get_offer or get_store_offers, which are never named. An agent can infer this is the discovery entry point, but nothing explicit routes it there versus the siblings.

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