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

Beyond the readOnly/openWorld/idempotent annotations, it discloses the answer contract (a yes/no always carries an exact quote and its source; not_known means nothing settles it; never a guess), the source scope (listing and store page only), a safety caveat, and a full error-recovery map including RATE_LIMITED wait 60 seconds. That is substantial behavior the annotations do not cover.

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 and answer semantics are front-loaded, and the routing/error content is genuinely useful, so little is wasted. It is nonetheless one dense block that crams quoting rules, safety advice, five error codes and next-step tools together, which slightly taxes scanning.

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-value burden well: it explains the three possible answers and that yes/no include the verbatim quote and source. Combined with the error-code recovery and next-tool pointers, an agent has everything needed to invoke and interpret the call.

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 the schema already documents fits, merchant, product_id and shopping_session_id. The description adds provenance and meaning beyond the schema—where merchant/product_id come from (search_catalog) and that the check is scoped to the listing, not the manual—but does not clarify the optional session field.

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 description gives a concrete verb (asks/checks) and resource (one listing vs. a named thing) and defines the answer space (yes, no, not_known). It explicitly distinguishes itself from the sibling ask_product_manual, so an agent can route between the two without opening their schemas.

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 states when to use it ('when a shopper asks whether a listing fits something they own'), where to source inputs ('take merchant and product_id from search_catalog'), and names the alternative with its selecting condition ('For what the maker's manual says ... use ask_product_manual'). Prerequisites and exclusions are all present.

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