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

Annotations only indicate non-readonly, non-idempotent, non-destructive. The description adds valuable behavioral detail: returns a URL for browser payment, funds are credited asynchronously, and the call is refused with billing_country_required until the country is known. This goes beyond the schema and annotations, though it omits auth or rate-limit expectations.

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 description is compact and front-loaded: the main purpose is in the first phrase. It uses three concise sentences and avoids fluff. The 'Minimum 10.' fragment is slightly abrupt but acceptable. Each sentence adds necessary operational detail.

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?

Given three simple parameters and no output schema, the description explains the return value (checkout_url) and the key behavioral constraint (billing_country refusal). It also clarifies the asynchronous funding flow. It could mention error cases beyond billing_country, but it covers the essential operational guidance an agent needs.

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?

Although schema coverage is 100%, the description enriches the billing_country parameter by explaining its purpose (invoice country), the VAT implication for the UK, and its practical requirement despite not being in 'required'. It also reiterates the minimum amount. Currency is not discussed beyond the schema default, but the added semantics are meaningful.

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 clearly identifies the action ('Create a Stripe Checkout link') and the resource ('add funds to the wallet'), and it specifies the key output (checkout_url). This distinguishes it from wallet balance or survey tools, so an agent can understand its role without opening the 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?

The description provides clear usage flow: generate the link, give it to the user, funds land after payment. It also explains when billing_country must be collected ('ask the user for it') and the failure mode if omitted. It does not explicitly mention alternatives or when not to use this tool, but the context is sufficient for correct invocation.

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