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

Annotations only set readOnlyHint=false and destructiveHint=false, so the description carries the burden of behavioral disclosure. It adds valuable context: the operation is a TEST mode PaymentIntent, it only creates a pending state, credits are not granted or spendable until confirm_credits, and it requires a caller key. This goes beyond annotations and clarifies side effects, though it omits details about failure handling or response format.

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 two tight sentences, front-loading the core purpose and immediately clarifying the pending state. Every clause adds value—test mode, intent-only, pending credits, and key requirement—with zero redundancy.

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?

With a single required parameter and no output schema, the description sufficiently covers the call flow: it states the action, the prerequisite key, the test environment, and the dependency on confirm_credits. It does not detail the response structure, but given the simplicity and the presence of confirm_credits, this is an acceptable gap.

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% and the parameter description already explains pack_id as coming from list_credit_packs with an example. The tool description adds no additional semantic meaning beyond what the schema provides, so the baseline of 3 applies.

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 the tool initiates a Stripe TEST PaymentIntent for a credit pack, specifies the endpoint, and explicitly differentiates itself from confirm_credits by noting the intent-only nature. This gives an agent a precise, unambiguous purpose that distinguishes it from siblings like quote_credits or list_credit_packs.

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 provides clear context: it is the first step in a two-step flow, explicitly naming confirm_credits as the subsequent required call. It also notes the prerequisite of a caller key. However, it does not explicitly state when NOT to use it or offer alternative selection criteria, leaving a small gap.

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