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

Annotations already declare readOnlyHint and openWorldHint, and the description adds the deterministic defaulting rule (en-US Accept-Language → amazon.com, otherwise amazon.se), which is genuine behavioral context. However, it never describes what is actually returned or what happens when keywords must be searched rather than an ASIN resolved, leaving the resolution behavior opaque.

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?

Two sentences, front-loaded with the transformation performed, then the parameter defaults. Minor redundancy: the marketplace/locale defaults are effectively stated twice within the same span.

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?

The description clarifies inputs and output shape for a read-only resolver with no output schema, which is most of what an agent needs. But with seven optional parameters and no required ones, leaving occasion and styleTag entirely unexplained means an agent cannot confidently decide whether to pass them or omit them.

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 baseline is 3. The description's marketplace/locale note largely restates the schema text for those two properties, and it says nothing about the two enum parameters occasion and styleTag, whose role in a resolver tool is genuinely non-obvious.

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 first sentence gives a specific verb (resolve) plus the accepted input forms (ASIN, /dp URL, keywords) and the output (marketplace URL), so the resource is unambiguous. It does not name or contrast a sibling such as search_gifts or browse_catalog, which keeps it short of a 5.

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?

It gives concrete guidance on how to pick marketplace/locale per user region and states both are optional, which is useful in-call guidance. It never says when to choose this tool over search_gifts or browse_catalog, nor when not to use it, so the usage is only implied.

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