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

Annotations only tell us it is a non-idempotent, non-destructive write. The description adds real behavioral context: the exact cost rule, that a payment link is returned, and that the transfer only takes effect once payment completes. The main residual gap is that it does not say what happens if the recipient never pays or whether the existing bearer retains any rights in the interim.

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 purpose is front-loaded in the first sentence and the cost, identity, and payment-link facts each follow in order. The Klein's-receipts framing is slightly ornate, but it does real work by motivating the doubling rule rather than being pure decoration.

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?

With no output schema, the description carries the burden of explaining the return value and does so ('Returns a payment link; the transfer takes effect once it is paid'). Combined with the cost rule and the identity-preservation note, an agent has everything needed to call this correctly and to set expectations for the user.

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 order_id, name, and email are already fully documented. The description reinforces the endorsement framing ('sent there' for the email) but adds no format, constraint, or edge-case detail beyond the schema, 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 and resource ('Pass a certificate to someone else') and immediately clarifies the identity semantics: the same serial and hash are endorsed to a new bearer rather than a new certificate being minted. That distinction separates it from creation/ordering tools and from a renouncement conceptually, without the agent needing another 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?

It conveys when the operation is appropriate and a hard precondition (cost is exactly double the initial purchase value and the shop won't go lower), which is genuinely useful routing information. However, it never names the obvious alternative, renounce_certificate, or explains when an owner should renounce rather than transfer, so the choice between siblings stays implicit.

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