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

With no annotations, the description carries the burden and does well: "static and free" discloses that no external calls or costs are involved, and it discloses extra domain behavior (EU membership means no customs to Poland) that an agent could not infer. It does not state return format or ordering, which keeps it off 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?

A single sentence, front-loaded with the action and count, followed by the returned field list and then the call-to-action. Every clause — field list, EU flag rationale, static/free — carries information an agent needs; nothing is padding.

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?

There is no output schema, so the description compensates by enumerating the returned fields and the count of records. For a zero-parameter static list tool, nothing further is required to call it correctly.

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. The description reinforces this by framing it as a static table lookup with no filtering or selection inputs, so an agent will not go hunting for a marketplace argument.

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?

Names a specific verb and resource ("List the 22 Amazon stores") and immediately enumerates the returned fields — code, domain, country, currency, NBP table, languages, EU flag. The phrase "the other amazon_* tools support" cleanly separates this reference tool from the action-oriented siblings amazon_compare, amazon_product and amazon_search.

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?

"Call it to pick marketplaces without guessing" gives a clear call condition, and "static and free" signals it is a cheap lookup rather than a metered call. It stops short of explicitly stating it should be called before the search/product/compare tools, but the precursor role is strongly implied.

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