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

Annotations only indicate non-read-only and non-idempotent. The description adds the key behavioral fact that no charge or funding occurs until Stripe confirms payment, and it points to the balance check as the verification step. This materially improves the agent's understanding of side effects.

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?

Three short sentences, front-loaded with purpose. The third sentence is slightly awkward ('Return and check get_credit_balance') but still compact and relevant.

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 side-effecting checkout tool with no output schema, the description could more explicitly state what is returned (e.g., the checkout URL) and clarify the payment flow. The schema and annotations cover credits and safety, but the return contract is left implicit.

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 single parameter is fully described with min/max and the price formula including get_access_options. The description adds nothing to parameter meaning, so it meets the baseline but does not exceed it.

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: 'Create a Stripe Checkout link for the authenticated key.' This clearly identifies the operation and distinguishes it from siblings such as get_credit_balance and create_guest_key.

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 frames usage: create a checkout link for the authenticated key, expect no charge until payment is authorized and confirmed, and follow up with get_credit_balance. It does not name alternatives or explicit when-not conditions, but the context is clear.

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