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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and non-destructive behavior, so the safety profile is covered. The description adds genuinely useful context beyond that: results are 'freshness-stamped' and the credit model ('1 credit, no data = no charge') tells the agent about billing and data availability 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?

Three compact clauses that are front-loaded with the core purpose and returned fields. The trailing plan/credit note is slightly tangential but brief and useful, so overall the text earns its place.

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?

With no output schema, the description does the work of enumerating return fields and adds freshness and billing context, which is enough for a single-parameter read tool. It lacks explicit routing guidance among the many sibling analytics tools, which is the main remaining 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?

Schema description coverage is 100% for the single 'domain' parameter, so the schema already carries the parameter meaning. The description only implies 'for a brand' via the domain, adding no syntax, format, or constraint details beyond the schema. Baseline 3 is appropriate.

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 resource (active promotions/discount codes for a brand) and enumerates the returned fields (code, discount type/value, min order, validity window). It is clear what the tool does, but it does not distinguish itself from sibling tools like get_discount_frequency_and_depth or get_most_discounted_products, so sibling differentiation is absent.

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 gives no when-to-use or when-not-to-use guidance and names no alternatives among the many discount/promotion-adjacent siblings. The only contextual note is the billing/plan detail, which is not usage selection guidance.

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