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

With no annotations, the description carries the full burden. It discloses key behaviors: amount limits, balance cap, automatic credit on payment completion, and the return of a checkoutUrl. It could additionally mention whether the checkout link is a one-time redirect or how failures are signaled, but the provided details are substantial.

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 sentences efficiently convey all essential information: action, mechanism, limits, automatic behavior, and return value. No fluff or repetition of schema details.

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?

Given only 2 parameters, no nested objects, and no output schema, the description is remarkably complete. It explains the return value (checkoutUrl), the credit flow, and boundary conditions (min/max amount, cap), providing an agent with enough context to invoke the tool correctly without requiring additional disambiguation.

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 100%, so the baseline is 3. The description adds value by summarizing the purpose of the amount parameter and adding the $500 balance cap, which is not in the schema. It also clarifies that api_key is the vm_live_ key, matching the schema's description.

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 a specific verb+resource: 'Add prepaid credits to your wallet via a Stripe Checkout link.' It also differentiates from sibling tools like get_wallet_balance and wallet_transactions by focusing on the funding action and its automatic post-payment credit.

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 implies when to use the tool (to add credits before making purchases) and explains the benefit ('buy instantly with no checkout redirect'). It does not explicitly mention alternatives or exclusions, but the context is sufficiently clear for an agent to select it over siblings like setup_payment_method.

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