读取明确规格和参考价（只读）

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

Beyond the annotations (readOnly, idempotent, openWorld, non-destructive), the description discloses real behavioral traits: unknown fields are never guessed, an explicit 'unsupported' result is returned when page structure cannot be parsed, and price_assessment is limited to verified spec reference prices with group-buy, discount, and shipping flagged as unknown. It also adds a prompt-injection safety stance (webpage and seller text is data, not authorization). An output schema exists, so return-value detail is partly covered elsewhere, keeping this at 4 rather than 5.

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 purpose and the spec-completeness constraint are front-loaded, and every clause carries content (scope limits, no-guess policy, unsupported sentinel, injection stance). It is dense and slightly run-on, but there is no filler.

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 annotations and an output schema already present, the description supplies what structured fields cannot: the completeness requirement for spec selection, the no-guess and unsupported behaviors, and the data-not-instructions rule. The main remaining gap is relationship to sibling tools (when to use this versus pdd_read_item or pdd_add_cart), which the description leaves unaddressed.

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 goods_id, budget_max, and spec_selection in detail. The description adds only a modest gloss — that the spec combination needs complete group names and values — which is largely restated by the schema's own wording. Baseline 3 is appropriate.

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 specific verb and resource: read page price and inventory associated with an explicit, complete spec combination (读取具有明确规格组合关联的页面价格库存). It is clearly narrower than a general item read, but it never names a sibling such as pdd_read_item or pdd_add_cart to make the boundary explicit, so it stops short of full sibling differentiation.

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?

Usage is implied rather than stated: the tool applies when a complete spec combination (full group names and values) exists, and it emphasizes stopping before confirmation. There is no explicit 'use this instead of X when Y' routing, and the important precondition about only using an already-opened, item-bound price panel lives in the schema rather than the description.

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