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

Annotations already declare it is a non-read-only, open-world, non-idempotent, non-destructive operation; the description adds genuinely new behavior: it only returns a checkout URL and never charges anything itself, and it refuses cases with no findings so no money is taken. This is exactly the kind of consequence-level context annotations cannot convey.

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, each earning its place: the action and return value first, then the no-charge clarification, then the refusal rule. No filler or repetition of the schema.

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 supplies the return value (checkout URL) and the refusal outcome. The membership path is only covered inside the parameter schema, so the prose alone is slightly incomplete for the full unlock flow, but nothing needed to invoke the tool is missing.

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 description coverage is 67% and the two optional parameters (plan, membership_token) already carry detailed inline descriptions covering pricing, the 25-bill cap, and immediate unlock behavior. The prose adds no further parameter meaning, so the schema-dominant 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?

States a concrete verb (begin payment) and the concrete outcome (unlock findings, dispute letter, phone script), plus the returned artifact (checkout URL). This is clearly distinguishable from siblings like get_case, get_case_outputs, or check_medical_bill.

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?

Gives a clear precondition for use and a failure case: a case with no findings is refused and the user pays nothing. It does not explicitly name an alternative (e.g. when to read a case for free instead of unlocking it), so it stops short of full when/when-not routing.

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