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

Beyond the annotations (destructive, non-idempotent, open-world), it discloses the required payments:write scope, that the first call is a no-op validation pass, that unknown fields are refused by name, and what the first call returns (summary + confirm_token). This is exactly the extra context the annotations cannot convey for a destructive two-phase operation.

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?

Front-loaded with the action and permission, then the two-phase protocol; no wasted sentences. The fragment "Two calls." is telegraphic and could be merged, but it usefully signals the pattern before the explanation.

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 destructive, no-output-schema tool it covers scope, confirmation protocol, and the first-call return payload. It omits what cancellation does downstream (irreversibility, effect on associated payments or links), which would matter most for a destructive action.

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 50%: confirm_token is documented in the schema, paylink_id is not. The description fully explains the confirm_token lifecycle (omit on call one, echo the returned token on call two), filling the schema's gap, but adds no meaning about paylink_id's format or provenance.

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 opens with a specific verb+resource ("Cancel a PayLink") that is unambiguous against siblings like create_paylink, get_paylink, and list_paylinks. It never names a sibling to distinguish from, but the cancel action itself is distinct enough that no further disambiguation is needed.

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 gives explicit procedural guidance: call once to preview, show the summary to the person, and only call again with the same arguments plus confirm_token after they agree. It does not mention alternative tools (e.g., get_paylink to inspect state before cancelling), so it stops short of full when/when-not coverage.

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