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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds that results carry active state and that codes_available means unredeemed unexpired codes, which is useful field semantics, but it says nothing about pagination behavior or result ordering.

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, front-loaded with the core purpose, with no filler. The second sentence is slightly tangential to a listing tool but does carry real information.

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?

An output schema exists, so return values need no explanation, and the read-only annotations cover the safety profile. However, for a filtered/paginated list tool with three parameters and multiple sibling discount tools, the description leaves filtering behavior and sibling selection unaddressed.

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 only 33% – "type" is documented in the schema while page and per_page are bare. The description does not explain the type filter, paging, or per_page limits, so it fails to compensate for the coverage gap despite there being room to do so.

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?

"List the store discounts and upsells with their active state" gives a clear verb and resource and adds the returned state, which separates it from pure lookup tools. It stops short of naming sibling tools like list_discount_codes, so an agent must infer whether discounts and discount codes are the same collection.

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?

There is no explicit when-to-use, when-not-to-use, or alternative routing guidance. The phrase "For bulk coupons" hints that a coupon-code detail tool exists elsewhere, but the description never tells the agent to use list_discount_codes for individual codes instead.

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