Remove promo code

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

Goes well past the annotations: it explains the resulting pricing state, the bundle-price exception, repeat-call behavior on an empty cart or no applied code, and the applied=false return signal. Annotation idempotentHint=true is corroborated rather than merely restated, and the no-op specifics add real context.

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?

Three short sentences, front-loaded with the action and its price effect, then usage, then edge-case safety. Every clause carries information an agent would otherwise have to guess.

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 no-parameter idempotent cart mutation with an output schema available, the description covers effect, routing, and no-op behavior. Nothing needed to invoke it correctly is absent, and return-format detail is left to the output schema.

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; baseline is 4. Nothing is missing, but no extra semantic value is possible here.

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+resource ('Drop the promo code from the cart') plus the effect on totals ('totals go back to full price'), with a useful caveat that a bundle price still applies. It is clearly distinguishable from apply_promo, which it names directly.

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?

States when to use it ('when the human no longer wants the code') and when it is unnecessary ('isn't needed before apply_promo, which replaces the code anyway'), naming the sibling that covers the alternative case. An agent can route between remove_promo and apply_promo with no inference.

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