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

With no annotations, the description carries the full burden and does disclose real behavioral context: affiliate links currently omit ?tag= because Associates IDs are unregistered, exposed via tagConfigured=false, plus a directive never to invent placeholders. It does not state whether the call hits the network or caches results, which 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?

Three short sentences, front-loaded with what is returned, then usage guidance, then the tag caveat. Every sentence carries distinct information an agent would otherwise get wrong.

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?

No output schema exists, and the description compensates by naming the three returned fields and the tagConfigured flag. Ordering, total count, and whether results are static across calls are unstated, which is a minor remaining gap for a static reference list.

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 tool takes zero parameters, so the baseline is 4 and there is nothing for the description to clarify on input side. Its field enumeration is bonus value aimed at output shape rather than parameter meaning.

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 ("List supported Amazon storefronts") and even enumerates the returned fields (id, domain, defaultLocale), which goes beyond the name. No sibling tool deals with marketplaces, so the agent can route to it unambiguously.

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?

"Prefer matching marketplace + locale to the end user" gives concrete downstream selection guidance, so the agent knows why it is calling this and how to choose among results. It stops short of naming explicit alternatives or when-not-to-call conditions, but for a zero-param enumeration tool little more is required.

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