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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description's added value is the security-relevant warning that source text is untrusted data rather than instructions, plus the note that only published/permitted content is visible. Both are real behavioral facts an agent can't get from annotations, though nothing is said about missing-ID or unpublished-product failure behavior.

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 short sentences with no filler; the scope constraint comes first, the sibling routing second, and the safety caveat last. Every sentence carries distinct information.

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 an output schema present, return values need no explanation, and the description covers scope, safety and one sibling boundary. It stops short of covering the search_products / compare_items relationships that a three-param read tool might still need to disambiguate.

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%, with each of id, locale and market_id documented including the locale/market_id dependency, so the baseline is 3. The description adds only the variant_id linkage to list_offers, which is a mild cross-tool hint rather than clarification of this tool's parameters.

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?

"Read published product identity, variants and permitted content" gives a specific verb (read), a specific resource (product) and an explicit scope (published / permitted). It also explicitly disclaims price data and routes that to a named sibling, so an agent can distinguish it from list_offers without opening either 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?

The description clearly states one alternative and its condition: prices live in list_offers, keyed by variant_id. It gives no guidance on when to use this versus search_products or compare_items, so the routing is partial rather than exhaustive.

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