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

Annotations already declare readOnlyHint=false, openWorldHint=true, destructiveHint=false, and the description is consistent with those. Beyond the annotations it discloses a critical runtime constraint — in-card Stripe is blocked in ChatGPT — and the alternative payment rails, which is genuinely useful behavioral context. It does not describe success behavior, but an output schema exists to cover that.

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 the most important constraint (do-not-use in ChatGPT) followed by the human and agent paths. Nothing is padded, though the whole text is guidance rather than tool description.

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 payment tool with an output schema, the description needn't explain return values, and it fully covers routing to alternatives. However, it never explains what creating a checkout does, what packageId resolves to at runtime, or what the caller gets back in practice, leaving a gap for an agent that decides this tool is actually appropriate.

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?

The description says nothing about any of the four parameters. With schema description coverage at 75%, the schema documents packageId, returnUrl, and stripeProductId (including the 'legacy override — omit' note), so the baseline of 3 is appropriate. The description adds no parameter meaning beyond the schema.

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 never states what the tool actually does — it never says it creates a Stripe checkout session. Instead it is entirely a routing notice ('Do not use in ChatGPT') plus pointers to sibling tools. The only sense of purpose comes from the title/name, so the description itself is essentially a redirect rather than a purpose statement.

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?

It explicitly states when NOT to use it (in ChatGPT, where in-card Stripe is blocked) and names the correct alternatives per audience: ucode_render_credits with a URL for humans, and ucode_agent_billing (USDC on Base via x402) for agents/bots. This is explicit when/when-not/alternatives guidance naming the exact sibling tools.

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