create_topup_link

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

With no annotations provided, the description carries the full burden and handles it well. It discloses the delayed-effect behavior (balance credited only after human pays), returns only a URL, is free to call, and has specific authentication constraints.

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?

Every sentence carries distinct value: purpose, no-money-moves behavior, usage trigger, parameter semantics, auth requirements, and an example. It is front-loaded with the core action and remains compact despite covering many essential facts.

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?

Covers purpose, side effects, timing of credit, when to use, auth, and the main parameter. It does not describe the exact shape of the returned response or mention optional redirect URLs, but for a simple one-required-parameter tool with no output schema, it is nearly complete.

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 0%, so the description must compensate. It explains the critical amountUsd unit and provides a concrete example. It does not explicitly define cancelUrl or successUrl, but their names and the optional uri format in the schema make their meaning reasonably clear.

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?

States a specific verb (create), a specific resource (Stripe Checkout link), and the goal (add credit to your balance). It clearly differentiates from siblings like create_baton or mint_token by describing a human-facing payment link and explicitly stating no money moves here.

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 says when to use it ('Use when you hit insufficient balance'), when not to use it ('not for x402 callers'), and what credentials are required. This gives an agent unambiguous context for choosing and invoking the tool.

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