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

Annotations already declare destructiveHint=true and openWorldHint=true, and the description adds genuinely new behavior: it returns the payment wallet address, exact crypto amount, a 30-minute expiry, and a status URL, and critically discloses that the purchased code/QR is emailed by Cryptorefills and never returned here. That last point is a real fulfillment gotcha an agent would otherwise not know.

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?

Four tight sentences with zero waste; the dependency and the return/fulfillment facts are front-loaded in a logical order. Every sentence carries information an agent needs.

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 destructive, open-world mutation with only one required parameter, the description covers the prerequisite, the return payload, the expiry window, and the out-of-band delivery of the purchased code. Even though an output schema exists, the email-not-returned warning is essential context that is complete for correct invocation.

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 100%, so the schema already documents both parameters, including that confirm_token comes from validate_order and its 10-minute validity and the FULLNAME_MISSING condition on full_name. The description largely restates the token's origin rather than adding syntax or format detail, so 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+resource ("Creates the real order") and implicitly contrasts with the sibling validate_order by calling this the real, final order versus the validation step. An agent can distinguish it from purchase_wizard and validate_order without opening a schema.

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?

Explicitly names the prerequisite (a confirm_token minted by validate_order) and the conditional case for full_name after FULLNAME_MISSING. It gives clear context for when the tool applies, though it never states an explicit when-not-to-use or names a competing tool for the read-only path.

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