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

The description discloses meaningful behavioral outcomes beyond the annotations: it consumes as much balance as needed, fully covered orders complete immediately with status paid, and partial coverage returns a payment_url. This gives the agent a clear model of the tool's side effects and conditional behavior.

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 sentences deliver the action, the prerequisite, the balance-consumption behavior, and the conditional outcome. Every clause earns its place, and the critical sequencing constraint is front-loaded.

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 the output schema exists, the description adequately covers the operation's flow and outcome. It could optionally mention the relationship to wait_for_payment, but the response's payment_url and the immediate-paid outcome are sufficient for an agent to proceed correctly.

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?

The schema covers code and locale, while the description adds the essential context that booking_uuid refers to a held booking and that the code is a Toots gift card code provided by the buyer. This compensates for the undocumented booking_uuid parameter and reinforces the meaning of the other parameters.

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 ('Applies'), a specific resource ('a Toots gift card code' to 'a held booking'), and a clear sequencing constraint ('after set_contact'). This clearly distinguishes it from sibling tools like redeem_pass and wait_for_payment.

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 context for when to use the tool: apply a buyer-supplied gift card code to a held booking after set_contact. It does not explicitly name alternatives or exclusion conditions, but the sequencing and purpose are unambiguous enough for an agent to route correctly.

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