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

Annotations cover the safety profile (readOnly, non-destructive, open-world), and the description adds substantial context beyond them: it costs credits, failed reads are free, sign-in is required, variants cap at 100 with variant_count, and missing fields produce warnings. The marketplace vs other_market seller semantics and ordering ('listed last') are behavior an agent could not infer from structured fields.

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?

Front-loaded with the core purpose, but the second sentence is a long run-on stuffed with nested parentheticals (variant details, seller explanation, marketplace flags) that is hard to scan. The content is mostly valuable, yet the packaging could be broken into structured clauses.

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, so the description must carry return-value meaning, and it does: variants, option_names, images, identifiers, description, seller, per-shop pricing/shipping/stock, reviews, and warning fields. For a four-parameter read with no output schema, nothing an agent needs to call it or interpret results is missing.

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 each parameter is already documented in the schema, including the format enum and max_credits budget semantics. The description adds only the routing meaning of url vs product_id and the notion that raw exposes the shop's own JSON, so baseline 3 is appropriate.

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?

Opens with a specific verb and resource: 'One product's details: by url, or by a product_id from search_products.' It explicitly names search_products as the source for product_id, which separates it from that sibling without either schema being opened.

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?

Gives clear entry-point routing (URL vs product_id from search_products) and conditions under which extra data appears ('When the shop's own page is read...'). It does not state when not to use it, e.g. whether search_products alone suffices for bulk listing, so it stops short of explicit exclusions.

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