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

Adds substantial context beyond the annotations: tokens are single-use, authentication is required, the call only stages an action and returns an actionId, the user should be told what the card will be charged before executing, and gross-vs-net handling is described. The annotations (readOnlyHint=false, idempotentHint=false) are consistent and extended by the two-step confirmation flow.

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?

A single dense paragraph that is front-loaded with the purpose before the when-to-use, gross/net, and fallback details. Every sentence carries operational weight, though the run-on structure costs a bit of readability.

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 two-step staging tool with no output schema, the description covers the return value (actionId), the required user confirmation, the follow-up call, and a fallback path. Nothing an agent needs to invoke it correctly is missing.

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 adds real semantic value by explaining the GROSS/NET split that governs sharedPaymentToken and creditCents and tying them to the insufficient-funds error fields. It goes beyond restating the schema without fully documenting every parameter (e.g. sessionKey, maxChargeCents).

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 and resource ('Stage adding funds to the balance by charging a Stripe Shared Payment Token') and is clearly distinct from siblings like createPaymentSession, payInvoice, and executeConfirmedAction. An agent knows exactly what this does without opening the schema.

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 names the triggering condition (a purchase like registerDomain/renewDomain/transferDomain/orderVps failing for insufficient funds), the follow-up tool (executeConfirmedAction with the actionId), and the fallback (createPaymentSession with a checkout URL). When-to-use, when-not-to-use, and alternatives are all covered.

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