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

Annotations declare non-read-only, open-world, non-idempotent, non-destructive, but the description adds the crucial behavioral fact that the call returns a link the user must open to actually pay — i.e., no charge happens here — plus the already-subscribed fallback to the billing portal. It stops short of covering link expiry, failure modes, or auth requirements.

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 clauses: what it creates, what it returns, and the already-subscribed edge case. Front-loaded with the action and pricing, zero 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?

With no output schema, the description correctly explains the return value (a payment link, or a billing portal link). For a payment flow it could still mention auth requirements or what happens if the Stripe call fails, but everything needed to invoke it correctly is present.

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 carry the parameter meaning, and it does: it ties the two pricing options (€5.99/month vs €47.88/year) to the MONTHLY/YEARLY enum, letting the agent infer which plan value to send. It doesn't discuss the YEARLY default or how plan affects anything else.

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?

Names a specific verb+resource (create a Stripe checkout for Koddeo Premium) and enumerates the exact benefits and prices. No sibling tool touches subscriptions, and the description makes that boundary obvious.

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?

States the outcome when the user is already subscribed (returns the billing portal), which tells the agent this tool is safe to call regardless of current state. It does not state explicit prerequisites such as being logged in, but with no competing subscription tool there is little ambiguity about when to use it.

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