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

Annotations already declare destructiveHint=false and openWorldHint=false; the description adds risk framing ('low risk, action=commerce.quote'), the guarantee that no business transaction is committed and no money moves, and the exact return payload. There is a mild tension between 'nothing is written' and readOnlyHint=false — a quote record is in fact created server-side — but this is a wording nuance rather than a material contradiction.

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: the capability and its safety profile come first, then the checkout handoff. Sentences are tight in English, though the full bilingual restatement roughly doubles the text without adding information for an English-reading agent.

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 correctly carries the return contract (quote_id/quote_hash, live stock and price snapshot) and the downstream usage rule. Combined with annotations covering the safety profile and a fully documented schema, an agent has everything needed to call this tool and use its result.

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% and all five parameters (items, shop_id, agent_id, payment_mode, idempotency_key) are documented in the schema, so the baseline is 3. The description mentions quote_id/quote_hash but those are outputs, not inputs, and it adds no further semantics for idempotency_key, payment_mode, or shop_id inference beyond what the schema already states.

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 and resource (build a cart quote) plus the exact scope (snapshot of live stock and price) and the returned identifiers quote_id/quote_hash. It explicitly distinguishes itself from the sibling commerce_checkout by naming it as the next step for payment, so an agent can route 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?

Gives an explicit when-to-use (to obtain a quote before paying) and names the alternative with the condition that selects it: 'To pay, pass the returned quote_id and quote_hash to commerce_checkout unchanged.' The handoff contract between the two tools is spelled out, including that the values must not be altered.

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