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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false. The description adds useful context by listing the returned data (discounts, codes, availability, redeemed counts) and the endpoint, though it does not cover error or auth behavior.

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 short sentences with no wasted words. The returned data is front-loaded before the endpoint reference.

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 simple read-by-id tool, annotations cover the safety profile and the schema fully documents the only parameter. The description also enumerates the returned fields even though no output schema exists, leaving no significant gap.

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 single coupon_id parameter is fully documented in the schema, including that it comes from givingfuel_list_coupons. The description only says 'by id' and adds no syntax or format detail beyond the schema, so the baseline of 3 applies at 100% schema coverage.

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?

States a specific verb and resource: 'One coupon by id' with returned fields including discounts, codes, availability and redeemed counts. The singular 'by id' scope distinguishes it from the list_coupons sibling 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?

Clearly implies retrieval of a single known coupon, and the schema description points to givingfuel_list_coupons as the source for ids. It does not explicitly state when not to use it or name alternatives in the description itself, but the context is clear.

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