billing.top_up

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

Discloses side effects ('opens a payment/deposit flow'), non-idempotency ('each call creates a new top-up'), and explains that balance is not immediately increased. Annotations already hint at open world and non-idempotent, but description adds concrete behavioral details.

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?

Three sentences cover purpose, usage, and side effects without redundancy. Information is front-loaded and every sentence serves a distinct purpose. No unnecessary words.

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 explicit usage guidelines, behavioral transparency, and presence of an output schema, the description fully prepares an AI agent to select and invoke the tool correctly. Covers when, how, and what happens, including side effects and retry logic.

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 100% with descriptions for both parameters. The description adds meaning by explaining the rail choices: xrp for agent with destination tag requirements, stripe for human checkout. This augments the parameter descriptions beyond the 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 clearly states the action ('Create a credit top-up intent') and the resource (account balance). It distinguishes from sibling tools like billing.balance (for inspection) and deploy.run (for deployment), specifying that this tool does not immediately increase balance.

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?

Explicitly states when to call (deploy.run failure with 402 or low balance in billing.balance) and when not to call (for balance inspection, use billing.balance). Provides precise guidance on rail selection and post-call steps (retry deploy.run after funds confirm).

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