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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, and openWorldHint=false. The description adds genuinely useful context beyond those hints: the return value is a Stripe payment link and a subsequent 402-challenge step completes payment. It omits other behavioral traits such as link expiry, data-size limits, or what happens before payment is settled.

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 short sentences with the core purpose front-loaded and no filler. The only inefficiency is the ambiguous, unexplained reference to 'paymentLink', which forces the reader to guess whether it is a tool, endpoint, or parameter.

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?

An output schema exists, so return values need not be described. However, for a payment-gated capability with four required undocumented parameters and a multi-step 402 flow, the description is thin: it never explains the inputs, prerequisites, or how this differs from the non-MPP sibling, leaving real 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 0% across four required parameters (data, encoding, consumer_id, invocation_context), so the description carries the full burden and adds almost nothing. Only a vague hint that 'the same arguments' are reused for the payment step is offered; no parameter is explained, and the 1.4M data cap and encoding enum are left to the raw schema.

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?

The description states a specific verb and resource: 'Return a Stripe MPP payment link for this Blue Cap capability.' Combined with the title referencing hash.compute, an agent can tell this is the payment-link variant of the hashing capability. It does not, however, explicitly contrast itself with the plain hash_compute sibling, so the differentiation is left to the name suffix.

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 a follow-up workflow step ('POST the same arguments to paymentLink to receive the HTTP 402 challenge and complete payment'), which implies when and how the tool is used in the payment flow. But it never states when to choose this over hash_compute, and 'paymentLink' is an undefined reference, so the guidance is only partially actionable.

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