Top Up With Card Mpp

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

Annotations declare the safety profile (non-read-only, open-world, non-idempotent), and the description adds rich behavior beyond them: 'Nothing is charged by this call,' single-use link valid 15 minutes, the 402/approval flow, immediate credit with new-balance response, and the --context minimum-length and fresh-wording 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?

Front-loaded with the core purpose and trigger, then flows into operational detail. Dense but nearly every sentence carries actionable guidance (context length, single-use, expiry, alternatives), though it runs long and could be trimmed slightly.

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?

No output schema exists, so the description carries the return burden and does: it returns a payUrl, the response shows the new balance, and the 402 terms flow is explained. Complete for an agent to invoke and interpret results.

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, but the description reinforces the amount_cents bounds of $5-$500 and the integer-cents semantics, adding context beyond the schema. dry_run is only covered by the schema, so it isn't a full 5.

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+resource: obtaining a payment link that adds account credit paid by CARD over MPP via a Stripe Shared Payment Token. It clearly distinguishes itself from siblings like top_up_with_usdc, sandbox_topup, and top_up_account_credit by naming the payment rail.

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?

Explicit trigger condition is given ('when a purchase failed with INSUFFICIENT_FUNDS and no card is saved at Porkbun'), plus named alternatives for when not to use it (top_up_with_usdc, manual top-up at porkbun.com, sandbox_topup for sandbox keys). Routes the agent well.

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