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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds genuine context beyond that by disclosing the returned fields and the cheapest-first ordering, which matters for how an agent presents results. It stops short of noting price freshness or what happens when no bundles are available.

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 what the tool returns and ending with the routing decision. The parenthetical phrase list earns its place by mapping natural user phrasing to this tool.

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 carries the burden of describing the return payload, and it does so field by field plus ordering. For a no-parameter, read-only lookup, nothing an agent needs to call or interpret it is missing.

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 there is nothing for the description to disambiguate; the baseline for a parameterless tool applies. The description correctly avoids inventing filtering options that the empty schema does not support.

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 names a specific resource (ready-made IMPOSSIBREW bundles) and states exactly what each result carries: live prices, can counts, price per can and a checkout link, ordered cheapest first. It also frames the audience ('someone who wants to try a few beers or find the cheapest way in'), which distinguishes it from browsing or custom-mix siblings.

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 explicit trigger phrases ('cheapest way to try', 'sampler', 'mixed pack', 'first order') and names the alternative, build_box, with the condition that selects it (custom mix). The when-to-use and when-not-to-use routing is fully spelled out.

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