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

Annotations only say readOnlyHint=false and destructiveHint=false, so the description adds meaningful behavioral context: confirming is the point where credits become granted/spendable and it appends credit.purchase with credits_added. This goes beyond the annotations and clarifies the side effect.

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 compact and front-loaded, stating the action, test card, endpoint, side effect, and TEST-only restriction in three short sentences. Every sentence earns its place with no filler.

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 one-parameter, no-output-schema tool, the description is complete: it says what to do, what source the ID comes from, what the effect is, and that it is TEST only. An agent has enough information to select and invoke it correctly.

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 description coverage is 100% and the single parameter is already well documented as the PaymentIntent id from checkout_credits. The description adds no new parameter-level detail, but it also does not need to, since the schema carries the full semantic load.

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 uses a specific verb ('Confirm') and resource ('a TEST PaymentIntent' for credits), and gives the endpoint. It clearly states the tool is TEST-only and explains the effect (credits become granted/spendable), which distinguishes it from checkout_credits and credit_balance.

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 establishes clear context: this confirms a PaymentIntent from checkout_credits and is TEST only. It implicitly tells the agent when to use it, though it does not explicitly name alternatives or give when-not-to-use exclusions.

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