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

The readOnlyHint annotation already establishes this is a safe read, so the bar is lower. The description adds the concrete API endpoint, which is mildly useful context, but says nothing about pagination behavior, result volume, or authentication needs beyond what the schema implies.

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 terse, front-loaded sentences with zero padding; the primary operation leads and the API detail follows. Slight redundancy with the schema's store_id description keeps it from a 5.

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 read-only list endpoint with four optional, fully documented parameters and no output schema, the description covers what an agent needs to invoke it correctly. Return-shape and pagination expectations are the only mild gaps.

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%, so all four parameters (include, store_id, page_size, page_number) are already documented in the schema. The description only echoes the store_id filter, adding essentially no meaning beyond the structured fields; 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?

States a specific verb (List) and resource (discounts) with the optional scope (one store), and the API mapping GET /discounts pins down exactly what is being called. It is not confused with get-style siblings, though it does not explicitly differentiate itself from them.

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?

'Optionally filtered to one store' implies the main use case, but there is no when-to-use/when-not guidance and no mention of alternatives (e.g. fetching a single discount vs listing all). Usage is implied rather than stated.

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