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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description still adds real value beyond them: it discloses affiliate disclosures, dated observations (data freshness caveat), and that it does not verify live stock or transact.

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 dense sentences with the primary purpose front-loaded and the caveats trailing. No filler, nothing restating the tool name.

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 3-parameter read-only tool with no output schema, this covers purpose, data provenance, and negative capabilities well. The only meaningful gap is guidance on the optional language parameter and whether market constrains it.

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 description coverage is 0%, so every parameter's meaning rests on the description. "Explicitly chosen buyer country" usefully clarifies that market is the buyer's country (not a store location) and "one machine" scopes machineId to a single ID, but the language parameter, its default, and the relationship between market and language are entirely unaddressed.

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 precise verb+resource ('Read existing retailer links') scoped to one machine and one buyer country, which cleanly separates it from the sibling calculators and finders. An agent knows exactly what this returns without opening the schema.

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?

"For one machine and an explicitly chosen buyer country" tells the agent the required input shape and implies no bulk or inferred-market lookups. "Never purchases or confirms live stock" sets a clear boundary, though no alternative sibling is named for related needs (e.g., machine comparison).

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