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

Annotations already cover the safe-read profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, and the description still adds real context: prices are observations that can drift, the retailer page is authoritative at checkout, and ambiguous names produce an other_matches list. What it doesn't cover — result ordering, empty-result behavior, or freshness thresholds for 'last checked' — are minor gaps.

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 sentences, front-loaded with the core behavior and result payload, then ambiguity handling, then the staleness caveat. The first sentence is long and stacks many return fields, but nothing is redundant or filler.

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 carries the return-shape burden and does it well: it names the fields returned and explicitly handles the multi-match case. It stops short of stating what an empty result looks like or whether results are ranked by price, which an agent calling a price-comparison tool would want.

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 single parameter already documents URL/slug/name forms with examples, so the description need not repeat it. It adds only a light hint that name lookups are fuzzy and may resolve to several models, which is marginal value beyond the schema's own description.

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: 'list the retailers that currently have it in stock' for one product, and enumerates what each result carries (price, configuration, last-checked, coupon, buy link). That is clearly distinguishable from search_products or top_deals, which operate over sets rather than a single product.

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?

Usage is implied by 'For one product' — an agent can infer this is the per-product lookup path — but the description never names an alternative or states when not to use it (e.g. when the product is unknown, use search_products first). No prerequisites or exclusions are given.

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