billing_machine_pay

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

With no annotations, the description carries the full behavioral burden. It discloses that the tool returns a POST URL and amount and that the agent must call HTTP with the MPP Payment credential—key information about side effects and what the agent must do next. It stops short of discussing idempotency or failure modes, but covers the central 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?

Three short sentences cover purpose, the parameter, and the required follow-up action with no filler. The most important operational detail—that the agent must call the returned URL with a credential—is stated directly.

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 tool with one optional parameter and no output schema, the description is close to complete: it mentions the default SKU, the return shape, and the next action. It does not specify where the MPP Payment credential comes from, but this is a minor gap given the simple contract.

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 0%, so the description must compensate. It adds the default value (pro_prepaid_30d) and confirms sku is optional. The enum values themselves are self-descriptive enough that listing them again would add little; the main semantic gap is not explaining when each SKU 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 states a clear purpose: unlocking Pro or purchasing agent SKUs via Stripe MPP, and explains the concrete deliverable (POST URL and amount). It is not a tautology and is distinguishable from siblings like usage_get and budget_get, though it does not explicitly name an alternative.

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 opening sentence makes the intended trigger explicit: use this when the agent needs to unlock Pro or buy agent SKUs. It does not provide exclusion criteria or name alternatives, but there are no close sibling payment tools, so the context is reasonably clear.

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