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

Annotations already declare read-only, idempotent, open-world, and non-destructive behavior. The description adds a crucial behavioral fact beyond annotations: variant IDs are only available from this result, which is key for downstream tool orchestration. It doesn't discuss rate limits or error cases, but with annotations covering safety, this is a meaningful addition.

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 with no wasted words. The return value is front-loaded, and the critical dependency note follows immediately. Every sentence earns its place.

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 output schema, the description adequately describes the return: product facts, current exact variants, and variant IDs. It also flags the key dependency that variant IDs only come from this call. The only gap is a lack of parameter explanation, but overall it is sufficient for correct invocation.

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% for the single 'id' parameter. The description implies the parameter selects 'one beer', but does not explain that 'id' expects one of the enum values (lager, pale, tipa, etc.). The enum itself is somewhat self-documenting, so this is minimally adequate but not compensating for the schema gap.

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 clearly states the verb (returns) and resource (product facts, exact variants, variant IDs) and scopes it to 'one beer'. It does not explicitly name sibling tools like browse_beers, but the singular scope distinguishes it well enough.

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?

Usage is implied: the tool fetches details for a single beer, and the note that 'Variant IDs exist only in this result' suggests it must be used before tools that need variant IDs. However, there is no explicit when-to-use, when-not, or alternative routing.

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