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

Goes well past readOnlyHint/openWorldHint by disclosing the size of the underlying pool (~40 hot keywords plus a few discovery/shading keywords per call), that ordering is AliExpress's own and not promised stable, and that search history is empty for anonymous callers. Those are exactly the traits an agent cannot infer from annotations; only the omission of error/rate-limit behavior keeps it from 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?

One dense paragraph that front-loads the resource description, then schemas-as-prose for limit, then exclusions, then the follow-up. Nearly every clause earns its place, though 'discovery and shading keyword modules' is unexplained jargon that costs a little reading effort.

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?

An output schema exists so return shapes need not be restated, and the description covers the remaining unknowns: what the feed contains, how big it is, how stable the order is, what is absent, and what to call next. Nothing an agent needs to invoke this correctly is missing.

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 already 100% for the single limit parameter, so the schema carries the range and default. The description still adds value by explaining the ~40-keyword pool, which tells an agent that raising limit past 40 has no effect and that limit controls pagination-style capping of a fixed feed.

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?

Opens with a precise verb+resource framing ('AliExpress's own discovery/trending search-keyword feed') and enumerates exactly what each item carries (display casing, category label, ready-to-use search URL) plus the extra discovery/shading modules. It also explicitly separates itself from product tools, so an agent can tell it apart from aliexpress_search and aliexpress_categories 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 explicit when-not guidance ('not products and not a personalized recommendation: no product ids, titles or prices are returned') and names the follow-up path ('Follow up with aliexpress_search using a returned keyword'). The routing decision is fully determined by the text.

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