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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the description is not needed for basic side-effect disclosure. It still adds real value beyond them: it tells the agent that the call reuses the original membership / successful-query count (a billing/quota consequence that appears nowhere in structured fields), and restates no-subscribe/no-charge/no-message as the explicit guarantee.

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?

One tightly packed sentence with the verb and resource front-loaded and the no-side-effect guarantee trailing as a qualifier — no filler. It is arguably undersized for a fifteen-field nested filter, but that shortfall is better attributed to completeness than to verbosity.

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?

For a tool whose input is a nested fifteen-property query object with enums and no output schema, the description says nothing about what comes back (quote list shape? limit semantics?) or how the filters interact. The only contextual support is the read-only annotations and the quota-reuse note, which is not enough for an agent to construct a correct query without opening the schema.

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?

The schema is a single required nested `query` object with roughly fifteen properties and effectively no descriptions, so the description carries the burden of explaining fields like time_basis, max_age_days, price_kind, mileage bounds, and limit. It explains none of them, adding zero meaning beyond the schema; only the schema's own price_kind description compensates for a small part of the gap.

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 (预览/preview) plus two concrete resources — the watch (盯车) conditions for the current model and the matching quotes — and explicitly rules out creating a subscription. It does not, however, differentiate itself from the close sibling search_quotes, which an agent could easily confuse with a quote-matching preview.

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?

Implied usage is clear enough: call this to inspect what a watch would produce before committing. The clause '不创建订阅、不收费或发送消息' signals it is a safe pre-check rather than a commitment, but no alternative tool is ever named, so the agent must infer the boundary with search_quotes on its own.

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