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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety profile is covered. The description adds useful context about tag behavior (tags omitted until real Associates IDs are registered, tagConfigured will be false), but does not describe other operational details such as caching or freshness.

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 sentences, each earning its place: what the tool returns, the required workflow, and the tag caveat. The information is front-loaded and efficient.

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?

With no input parameters and no output schema, the description carries most of the explanatory burden. It covers the returned fields and the marketplace prerequisite well, though it could say more about freshness or when marketplace data changes.

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 has zero parameters, so the schema provides no per-parameter information to supplement. The description does list the fields returned, which is helpful context even though parameter semantics are not applicable.

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 and resource ("List supported Amazon storefronts") and enumerates the returned fields (domain, label, currencyHint, tagConfigured). It distinguishes itself from siblings by positioning the result as input to search/resolve/create.

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 clear, imperative usage guidance: "Agents MUST pick the user's marketplace and pass it on search/resolve/create." That establishes the prerequisite workflow without stating when-not-to-use conditions or naming alternative tools.

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