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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful context beyond that: the coupon is replicated into the business's connected Stripe account (an external side effect), and 'Buyers type the code at checkout' explains the downstream behavior. It does not address error/duplicate-code handling, keeping it short of 5.

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 action ('Create a discount code') does not appear until the third sentence; the two preceding sentences are domain preamble about the chat not selling anything. The content is not bloated overall, but it is not front-loaded and the opening framing is somewhat expendable.

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 9-parameter create tool with full schema coverage and no output schema, the description supplies the domain, the two discount modes, and the Stripe replication side effect. It omits return-value behavior and what happens on a duplicate code, but the structured schema plus annotations carry the rest, leaving it nearly complete.

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 every parameter is already documented in the schema, including the percentOff/amountOff exclusivity and the idempotencyKey semantics. The description restates the percentage-vs-fixed-amount choice but adds no format or constraint detail beyond what the schema carries, so the baseline of 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 and resource ('Create a discount code for the store') and enumerates the two modalities (percentOff vs amountOff plus currency). An agent can tell it apart from list_coupons and set_coupon_active by inference, but the description never names those siblings explicitly, so it stops short of full differentiation.

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 'Store administration' framing and the note that buyers use the code at checkout give implied context for when this applies, and the scope is clarified as the business's own store rather than a marketplace. However, there is no explicit when-to-use/when-not guidance or routing against siblings like set_coupon_active or update-style alternatives.

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