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

Beyond the readOnly/idempotent annotations, the description discloses non-obvious behavior: a 60-second fresh cache, serving cache for up to 5 minutes with background refresh, an optional force_refresh, quota not re-charged when switching model years, and card-first delivery with no local files, no shell commands, and no HTML generation. These are genuinely useful disclosures. The only weak spots are the vague closing clause about future values being published only after validation.

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?

The text is one dense block of semicolon-separated clauses that leads with low-level parameter constraints instead of the tool's purpose, and it mixes schema rules, caching behavior, and output formatting without headings or ordering. The content is largely substantive, but the lack of front-loading and structure forces the reader to parse the whole paragraph to extract the call contract.

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 complex nested-schema tool with no output schema, the description covers the essentials: what is returned (quotes, years, history distribution, interactive card), how compact versus full responses differ, and freshness and caching semantics. That is enough for an agent to call it correctly, though the return shape details are conveyed loosely rather than systematically.

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?

With 0% schema description coverage on a 14-property nested object, the description compensates substantially: it explains the query nesting rule, that history_days and response_mode sit at the outer level, that city and province are mutually exclusive and must not be null, that numeric fields take integers, that trim must be the full string from get_vehicle_choices including the year prefix, and what compact versus full return. It still leaves limit, the price and mileage ranges, time_basis, and max_age_days unmentioned.

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 states a concrete verb and resource set: return recent quotes, selectable model years, and a real historical weekly quote distribution over 7–365 days, plus a native interactive card. That makes the tool distinguishable from get_market_insight and compare_quote. However, this purpose statement is buried after several clauses of parameter constraints, so an agent must read to the middle of the paragraph to learn what the tool actually does.

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 gives real routing guidance: do not repeat a query for a second price column, prefer response_mode=compact in conversation but use 'full' when per-item full text is needed, use delivery_status to avoid redundant queries, and use get_vehicle_choices for the complete trim string. It does not explicitly say when to choose this tool over get_market_card or search_quotes, so sibling differentiation is only partial.

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