factreason_create_topup_link

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

The description goes beyond the annotations by disclosing that this tool creates an external checkout session, does not charge a card, and that credit is applied only after human payment. It also notes the tool itself is not metered. These are valuable behavioral insights that annotations do not provide, and there is no contradiction with the given hints.

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 concise and well-structured. The opening sentence clearly states the primary purpose, and the following sentences build on it with essential usage and behavioral details. No unnecessary words or repetition are present.

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 tool with one parameter and an output schema, the description covers all necessary context: what the tool does, when to use it, limitations, and how the results should be handled. The existence of an output schema covers return values, so no further description is required.

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 input schema already provides full coverage for the single parameter 'amountUsd', including a description, minimum, maximum, and common block values. The tool description adds little new information about the parameter beyond the schema, so the baseline of 3 applies.

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 tool's function: 'Create a Stripe Checkout URL for adding prepaid credit to the calling Bearer API key.' It uses a specific verb ('Create'), names the resource ('Stripe Checkout URL'), and specifies the context ('adding prepaid credit'). This clearly distinguishes it from the sibling tools, which focus on API discovery, advisories, and schema changes.

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 explicit usage guidance: 'Use after HTTP 402 or when balance is low.' It also explains what not to do ('You CANNOT COMPLETE THE PAYMENT YOURSELF') and instructs the user to return the URL to a human. This gives clear when-to-use and when-not-to-use context, fulfilling the top criterion.

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