haul_topup_credits

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

With no annotations, the description carries the behavioral burden. It discloses that the tool returns a URL the user can open, which implies user involvement, but it doesn't explain side effects like whether a Stripe checkout session is created, whether credits are only added after payment, or whether the URL expires.

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 short sentences with no wasted words. The core action is front-loaded, and the output expectation is stated clearly.

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 simple one-parameter tool with full schema coverage, the description sufficiently conveys the purpose and return value. It lacks optional details like checkout URL expiry or confirmation behavior, but those are not essential for a basic call.

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 already documents the single parameter fully, including the enum values and a description. The tool description adds no additional parameter semantics, so the baseline of 3 is appropriate.

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 names a specific action ('Get a Stripe checkout URL') and a clear resource scope ('buy more HAUL credits'). It clearly distinguishes itself from the sibling tools, which are about verification, balance checking, and listing tools.

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 phrase 'to buy more HAUL credits' gives clear context for when to use the tool. It doesn't explicitly mention when not to use it or name alternatives, but the purpose is distinct enough from siblings that an agent can confidently select it.

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