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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so safety is covered. The description adds real value beyond that by enumerating the returned attributes (type, value, applicability, dates, status) and the REST path, telling the agent what a call will yield without opening the schema.

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 filler; the resource definition and returned fields come first and the endpoint trails as supporting detail. Nothing redundant.

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 read-only, no-required-param listing tool with full schema coverage and clear safety annotations, the definition covers what an agent needs to invoke it. The only real omission is the lack of routing guidance relative to the discount-code and automatic-discount listing siblings.

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%: both page and limit are documented in the schema, including defaults, bounds, and the instruction to pass the previous reply's next_page. The description adds nothing about pagination, so the baseline 3 applies.

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?

Names a specific verb and resource ('List sale promotions') and parenthetically defines the resource as 'price reductions on products', which disambiguates it from a generic list. It also gives the backing endpoint. It stops short of distinguishing itself from the near-neighbours list_discount_codes and list_automatic_discounts, which an agent could easily confuse with sale promotions.

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 contains no when-to-use or when-not-to-use guidance. With three similarly named listing siblings (discount codes, automatic discounts, sale promotions) the agent is left to infer from the parenthetical definition which one applies to a given request.

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