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

Beyond the annotations, the description discloses two useful behaviors: it will not fabricate a tracking tag and omits ?tag= until real affiliate IDs exist, and it returns both buyUrl and affiliateUrl. The phrase 'dual-writes affiliateUrl' is imprecise and could be misread as a side effect, but in context it describes response enrichment, consistent with readOnlyHint=true.

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 tight sentences, front-loaded with the core action, then the tagging caveat, then the mandatory-parameter directive. Nothing is redundant.

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 7-parameter, read-only lookup with no output schema, the description states what comes back (buyUrl plus affiliateUrl) and covers the key constraint (no fabricated tags, marketplace/locale required). It could optionally explain how asin/url/keywords are prioritized when several are supplied.

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 71%, so the schema carries much of the load, but the description adds real meaning: it frames asin/url/keywords as alternative identification methods and stresses marketplace + locale as mandatory. The genre and platform enums are left to the schema, which is acceptable given their self-describing values.

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?

Uses a specific verb + resource (resolve -> buyUrl) and enumerates the three accepted input forms (ASIN, pasted /dp/ URL, keywords), which is much more specific than the title alone. It does not reference any sibling tool, so differentiation is implied by the 'resolve' semantics rather than stated.

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 listed input forms imply when to use it, and 'ALWAYS pass marketplace + locale' is an explicit invocation constraint the agent can act on. There is no when-not guidance and no named alternative (e.g. search_gifts or get_catalog) for catalog browsing.

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