kfc_promotion

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds valuable context: serialized-code lookups return additional usage metadata (list of field names), and unknown/expired codes return a 404 instead of a null payload. This goes beyond the schema and gives the agent a clear model of edge case behavior. It does not mention rate limits or auth, but for a read-only lookup these are not critical omissions.

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 description is concise yet comprehensive. Each sentence serves a distinct purpose: definition of the tool, explanation of both code types, the mutual-exclusivity constraint, the serialized metadata bonus, and the 404 error behavior. It is front-loaded with the primary action and resource, with no redundant phrasing or boilerplate.

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?

Given the moderate complexity (two parameters, no output schema, no annotations), the description covers the essential context: what inputs are needed, what the output looks like (promotion plus optional metadata), and error handling. It does not enumerate all fields of the returned promotion object, but that is not critical for an agent to invoke the tool correctly. The description provides enough context for a confident call.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning beyond the schema. It clarifies the redemption code as 'the code a customer types in at checkout' and serialized code as 'a unique per-print QR/serial code' that resolves to a shared code. This explanation helps agents distinguish the two parameters and make correct selections, going beyond the schema's minimal descriptions.

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 tool's action ('Look up'), the resource ('one KFC promotion'), and the two accepted identifiers (redemption code or serialized code). It explains both code types in relation to checkout and printed coupons, and explicitly distinguishes this lookup operation from any search/browse functionality. The verb+resource structure makes the tool's purpose immediately unambiguous.

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?

The description explicitly states 'Exactly one of code or serialized_code is required', which is a clear usage constraint. It also explains when each code type is appropriate (customer checkout code vs. per-print QR/serial code). However, it does not name alternative tools or explicitly say when NOT to use this tool (e.g., when looking up promotions by category), so some inference is still required for tool selection among the large sibling set.

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