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

Annotations already declare readOnly, idempotent, non-destructive, open-world, but the description adds behavior they do not cover: rate limiting with a 60-second wait, a price_not_fresh retry-in-a-minute case, and a per-error-code recovery map that distinguishes store-scoped errors from generic ones. That is meaningful operational context beyond the structured safety hints.

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?

Purpose is front-loaded and the paragraphs are ordered sensibly (what it returns, when to use, when not, next steps, errors). The enumerated error-code list is long and partially redundant with the 'Full guide: get_tool_guide' pointer, which costs some tightness, but each line still carries actionable recovery guidance.

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?

There is no output schema, and the description compensates by naming the returned fields (variants, availability, price, currency) and the response_format effect. Combined with the error-recovery map and rich annotations, an agent has everything needed to call this correctly and handle failure.

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 all five parameters are already documented, and the description adds only provenance for merchant/product_id ('send merchant as the store slug search_catalog returned'), which overlaps the schema text. Baseline 3 is appropriate; it does not extend the schema with new format or edge-case semantics.

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 first sentence states a specific verb and resource plus the scope of the return: a single published product record with variants, availability, and the store's price and currency. It explicitly distinguishes itself from search_catalog (browsing), check_product (checked facts), and create_checkout (buying), so an agent can route without opening any 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 gives an explicit trigger (you hold a product_id or the number in a store page URL), explicit exclusions ('Not for browsing the catalogue; use search_catalog'), and named alternatives for adjacent intents (check_product for sourced facts, create_checkout for purchasing). It even adds a 'Next:' hand-off path, leaving little to inference.

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