post_prepaid_refill

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

No annotations are provided, so the description must convey behavioral traits. It indicates a mutation (refill) but does not disclose whether the operation is reversible, what happens to existing balance, or any required permissions. Additional context about side effects or restrictions would improve transparency.

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 a single, concise sentence with no unnecessary words. It efficiently communicates the core action and a key detail (payment method).

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 no output schema, the description is largely sufficient. It conveys purpose and payment method. However, it could be more complete by indicating whether the refill is additive or replaces existing credits, and what the response looks like.

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 describes the single parameter 'apiKey' as 'The prepaid API key to refill', and schema coverage is 100%. The tool description adds no extra meaning beyond the schema, so a baseline score 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 clearly states the action ('Refill a prepaid API key') and identifies the payment method ('x402 payment'). It differentiates this tool from sibling tools like 'post_prepaid_create' (create new) and 'prepaid_info' (query info).

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?

While the name and description imply refilling an existing key, there is no explicit guidance on when to use this tool versus creating a new prepaid key or checking info, nor are there any prerequisites or constraints mentioned.

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