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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds no further behavioral context beyond fetching details, which is consistent with the annotations. It does not mention any additional behaviors such as availability of deleted promotions or authorization requirements.

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 a single, concise sentence that front-loads the verb and resource. It contains zero filler and conveys the core purpose efficiently.

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 single-parameter getter with a comprehensive output schema and strong annotations, this description is mostly complete. It adequately communicates what the tool does, though it leaves out any mention of how to obtain the ID or any scope (e.g., company-level) – but these are likely implicit in the system's design.

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 input schema fully describes promotionId with the description 'The promotion ID', achieving 100% schema coverage. The tool description adds no extra meaning beyond implying that the ID targets a specific promotion, so it does not improve upon the schema.

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 action ('Get details') and the resource ('a specific promotion/coupon code'), which unambiguously distinguishes it from listing all promotions or mutating them. The specificity of 'a specific promotion' aligns with the single-ID parameter and the tool's name.

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 implies usage for retrieving a single promotion by ID, but it does not explicitly state when to use this tool over alternatives like list_promotions or validate_promotion. No exclusions or alternative mentions are provided, leaving the context implicit.

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