credits_checkout

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

With no annotations, the description carries full burden. It discloses the primary output ('Returns a checkout_url') and valid bundle options, which is useful. However, it does not mention potential side effects, prerequisites (e.g., authentication), or error behavior (e.g., invalid bundle handling). For a payment tool, more transparency about the actual charge and session behavior would be expected.

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 concise and front-loaded with the primary purpose, followed by the main output and valid bundles. The Args section is clean and directly useful. Every sentence contributes meaning without unnecessary fluff, making it well-structured.

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?

Given that an output schema exists (and the description already mentions the key output), the description covers the essential inputs and valid values. It lacks information about error cases, authentication requirements, or whether the checkout session is immediately charged, but for a straightforward purchase tool, it is reasonably complete. The 0% schema coverage raises the burden, but the Args section mitigates this.

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 0%, so the description must fully compensate. It does: the Args section explicitly explains both bundle (listing valid values) and return_url (optional, purpose). This adds significant semantic meaning that the schema itself lacks, making parameter understanding clear.

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 a specific verb+resource: 'Create a Stripe checkout session to purchase a credit bundle.' This distinguishes it from siblings like list_credit_bundles (listing) and get_credit_balance (querying). It is unambiguous about what the tool does.

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 usage is implied: it is for purchasing a credit bundle and returns a checkout URL. However, it does not explicitly state when to use this tool versus alternatives, nor does it mention any exclusions. The description gives context (valid bundles, return_url) but lacks direct guidance on selecting this tool.

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