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

Annotations already cover the safety profile (readOnly=false, idempotent=false, destructive=false, openWorld=true). The description adds genuinely useful behavior: credits are applied only after Stripe reports the session paid, the returned URL must be opened as-is to keep the Stripe fragment, and an API error is returned when Stripe is unconfigured.

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?

Front-loaded with the core action, then the endpoint mapping, return value, and payment-settlement caveat. Four tight sentences with minimal waste; the credit-range restatement is the only mildly redundant element.

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 return-value burden and does so by describing the checkout URL and the unconfigured-Stripe error. Combined with full parameter coverage from the schema and annotation safety hints, an agent has enough to invoke it correctly, though sibling disambiguation remains missing.

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 the schema already documents credits, wallet_id, and api_key fully. The description's restatement of the 100–100000 integer range and endpoint equivalence adds little beyond what structured fields provide, so the baseline of 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 ('Start a Stripe Checkout credit top-up') and even names the REST endpoint it mirrors, so the agent knows exactly what happens. It does not, however, distinguish itself from the sibling 'purchase' tool, leaving the agent to infer which one to pick.

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?

Use is implied (buying credits via Stripe's hosted checkout), but there is no explicit when-to-use or when-not-to-use guidance, and the near-identical sibling 'purchase' is never mentioned. The agent must guess between them.

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