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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses that only storefront-public promotions are returned (not private ones) and that a store with no active promotions yields an empty list rather than an error. These are the operational facts an agent needs, though no rate-limit or pagination behavior is mentioned.

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?

The purpose, field list, failure behavior, and alternative are front-loaded in a compact space with no filler sentences. Minor redundancy in restating store_number and a small wording slip ('retrieve look up') keep it off 5.

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 a single well-documented parameter, annotations covering the safety profile, and an output schema present, the description covers everything else an agent needs: scope (public only), empty-result semantics, code handoff to kfc_promotion, and the alternative tool. Nothing essential 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?

Schema description coverage is 100%, so the store_number semantics are already documented in the schema. The description restates the required/alphanumeric/source detail without adding format or validation meaning beyond what the schema provides, so baseline 3 is appropriate.

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?

Specific verb (returns) plus a precisely scoped resource (one restaurant's current public promotions), including exactly which fields each promotion carries. It clearly distinguishes itself from the sibling kfc_promotion, which is scoped to a single promotion. An agent can tell the two apart without opening either 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?

It names the alternative (kfc_promotion for lookup by redemption code/serialized code) and gives the selection condition, and it tells the agent where store_number comes from (/kfc/stores or /kfc/nearby). It doesn't state explicit exclusions for kfc_promotions itself, so it falls just short of a full when/when-not treatment.

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