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

With no annotations, the description carries the behavioral burden and does well: it discloses the feature is coming soon, returns a Stripe-hosted checkout_url, requires a verified owner/admin key, delays credits until Stripe confirmation, and returns 503 checkout_not_enabled until enabled. Minor gaps like link expiry or rate limits remain, but the key operational traits are present.

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 dense and front-loaded, putting the core action and return value first before pricing, payer instructions, auth, and availability caveats. It is appropriately sized for the amount of operational context, though the parenthetical pricing makes it slightly cramped.

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 two-parameter, no-annotation tool without an output schema, the description covers what is returned (checkout_url), the feature's availability (coming soon, 503 until enabled), auth requirements, and post-payment behavior. It is nearly complete, with only minor operational details like link expiry left unstated.

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 50%: the idempotency_key parameter is documented in the schema, while the pack enum is not described there. The description adds useful pricing and intent for pack_5, pack_20, and pack_100, but does not further explain the idempotency key's behavior beyond what the schema already says.

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 states that this creates a Stripe-hosted checkout URL for a credit pack intended for a human payer, which is a specific verb and resource. It could more explicitly distinguish itself from sibling tools like get_topup_link, but the card-checkout framing is clear.

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 meaningful usage context: use this for a human paying by card, give the link to that person, and credits arrive only after Stripe confirms. However, it does not explicitly say when to choose this over sibling alternatives such as get_topup_link, and the 'coming soon' state is noted but not tied to a routing decision.

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