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

Annotations already declare readOnlyHint and openWorldHint, and the description reinforces non-mutation ("Does not modify the store") while adding genuinely new context: a per-result price ($0.01), the heuristic (non-authoritative) nature of the score, and an explicit scope exclusion of certification/checkout testing. It stops short of describing latency, failure modes, or what happens with an unreachable domain, so it is strong but not exhaustive.

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?

Two dense sentences, front-loaded with what is audited, then boundaries, price, and alternatives. No filler sentences, though the opening clause stacks several audit dimensions and reads more like a spec list than prose.

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 and full schema coverage, the description fills most remaining gaps: cost, heuristic caveat, sibling routing, and non-mutation. The only omission is operational behavior on edge cases (invalid or unreachable domains) which an agent might want before spending $0.01.

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 both parameters are documented there, including the domain format constraint (no scheme/path/port) and the optional context field. The description adds no parameter-level meaning, so the baseline 3 applies; the schema does the heavy lifting.

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+resource ("Store audit") and enumerates the exact dimensions checked: machine-readable product data, UCP/ACP discovery, payment hints, robots.txt access, plus a heuristic score and prioritized fixes. It is immediately distinguishable from the product-level and trust-check siblings, which it names explicitly.

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 the positive case ("Use to diagnose agent-readable store discovery and prioritize fixes") and routes to two concrete alternatives with the conditions that select them (universal_product_url_to_json for one product, pre_purchase_merchant_trust_check for purchase-risk evidence). It also states a negative boundary: "Not a certification or checkout test."

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