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

Annotations only declare readOnlyHint=true, and the description adds real behavioral context beyond that: only already-published products are candidates, claimed products are boosted in ordering, and the feed is stateful across calls via exclude. It does not say whether ordering is randomized per call or per user, nor what a returned product contains (no output schema exists), which keeps it below a 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?

Three short sentences, front-loaded with the trigger condition, then the behavior, then the continuation rule. Every sentence carries distinct information and nothing is repeated from the schema.

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 two-parameter read-only feed with no output schema, the description covers when to call it, what population is sampled, how results are ordered, and how to paginate. The only real gap is the shape of a returned item, which an agent must learn by calling it.

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%, so limit and exclude are already documented in the schema. The description's continuation hint (pass seen product ids into exclude) restates the schema's own wording rather than adding format or semantics, so the baseline 3 applies.

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 (随机抽已发布的产品) plus a ranking rule (已认领主理人的产品优先), which is exactly the kind of detail that distinguishes it from the many list_*/search_* siblings. An agent can tell it apart from search_products and personalized_feed without opening a 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 concrete user phrasings that should trigger it (「随便看看」「让我发现些有意思的」「给我推荐点东西」) and explicitly names search as the alternative, with the condition that selects this tool: 「我也不知道我想要什么」. Nothing is left to inference.

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