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

Annotations already establish that this is a read-only, non-destructive, non-open-world operation. The description adds useful behavioral context beyond the annotations: it returns only curated public-MCP-visible promotions still active in commerce data, and it warns that final eligibility and stacking are revalidated by first-party checkout.

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 three short sentences with the core scope front-loaded, followed by filter optionality and the checkout revalidation caveat. There is no redundant or filler language.

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 low-complexity read-only listing tool with annotations and no output schema, the description covers the important scope and caveats. It is slightly incomplete on parameter semantics, but the schema provides constraints such as the productRef pattern and billingCycle enum values.

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 description coverage is 0% for two parameters. The description only says product and billing-cycle filters are optional, which is already implied by the schema having no required parameters; it does not explain the productRef slug format or the meaning of the billingCycle enum values.

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 states a specific verb (list) and resource (promotion codes), and narrows the scope to codes explicitly curated for public MCP visibility and still active in current DotMoose commerce data. That scope makes the tool's purpose clear without needing to open the 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?

The description implies when to use the tool by naming the promotion-listing resource and noting optional product and billing-cycle filters. It does not explicitly say when not to use it or name alternatives, and the checkout revalidation note is behavioral context rather than usage guidance.

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