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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuinely new disclosure: agents may share the code freely with any human, and no auth/wallet/x402 is needed. It omits expiry or single-use characteristics of the code, keeping it at a 4.

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 short sentences, front-loaded with what you get, followed by return contents and sharing/licensing terms. Every sentence adds a distinct fact; the only mild overlap is the repeated word 'free', which is not wasteful.

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?

There is no output schema, and the description compensates by naming exactly what is returned: the code, plain terms, redemption steps and store links. Combined with the annotation coverage, an agent has everything needed to call and use it.

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?

The tool takes zero parameters and the schema is fully closed, so there are no parameter semantics to explain; a 4 baseline applies. The description correctly implies no input is required.

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 ('Get the free, shareable code for 10 percent off') and pins down the scope: all five Rebecca Belle Boutique stores via Stripe checkout. It is unmistakably distinct from the sibling payment/purchase tools because it explicitly yields a coupon rather than moving money.

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?

It gives clear context for use (retrieve a discount code to hand to a human) and distinguishes itself from paid siblings by noting no account, wallet or x402 payment is required. It does not name a specific alternative tool or state an explicit when-not, so it stops short of a 5.

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