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

Annotations only declare readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false. The description goes well beyond them: no charge at call time, per-address refusal with named reason, delivery by e-mail plus a second e-mail after the night's seal, and the fact that no purpose is collected. That is exactly the behavioral context an agent needs and cannot get from structured fields.

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 purpose is front-loaded in the first sentence, but the paragraph is a single run-on stream with redundancy (address count/domain repeat the schema, and the fees URL is tacked on). The behavioral detail earns its place, but tighter sentence structure and removal of schema echoes would improve it.

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 carries the return burden and largely does so: a payment link page is returned, refused addresses are named with reasons, and results arrive by e-mail. It does not specify the exact return shape or error object, leaving a small gap for a mutating tool.

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 100%, so the schema already documents email, language, timezone and addresses. The description's 'up to twenty public addresses, all on the same domain' and 'only addresses are asked for, never a purpose' largely restate the schema rather than adding format or constraint detail, so the baseline 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?

The description states a specific verb and resource: 'Create a payment link for a point-in-time record' of named public addresses, with clear scope (up to twenty, one domain). It is not a tautology of the name/title. It does not explicitly differentiate itself from siblings like check_coverage, whose pre-validation role it silently absorbs, so it stops short of a 5.

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 strong usage context: the call charges nothing, validation happens automatically before link creation, and the capture only starts after a person pays on the returned page. However it never names an alternative tool or states when NOT to use this one, so the routing guidance against check_coverage/capture_status is left implicit.

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