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

Annotations already declare read-only, idempotent, and non-destructive behavior, so the description doesn't need to restate that. It adds a small amount of context (e.g., 'authoritative' implies a trusted data source, and the listed fields hint at return behavior), but it does not disclose additional operational traits like data freshness, latency, or error handling. With strong annotations, this is sufficient.

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?

A single, tightly written sentence front-loads the action ('Look up one AliExpress product by its numeric ID') and follows with a compact list of outputs. There is no repetition, filler, or extraneous detail; every word contributes meaning.

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 one-parameter, read-only tool with no output schema, the description adequately covers the input format, the tool's scope, and the full set of returned values. It doesn't address error cases or unavailability, but the simplicity and the provided annotations make this sufficiently complete.

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 provides full 100% coverage of the single parameter with a clear description ('Numeric AliExpress product ID') and a regex pattern. The description merely restates 'numeric ID' without adding new format or value semantics, so it relies on the schema and earns the baseline 3.

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 uses a specific verb ('Look up') with a clear object ('one AliExpress product by its numeric ID') and enumerates all the details returned (price, rating, sales volume, commission rate, category, cashback levels). This clearly distinguishes it from siblings like search_products, which would be used for discovery, and calculate_cashback, which focuses solely on cashback math.

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?

The phrase 'by its numeric ID' establishes a clear context: use this when you have a specific product ID and need authoritative details. It does not explicitly name alternative tools or state when not to use it, so it falls short of the explicit/exclusive guidance that would earn a 5.

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