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

Annotations already establish readOnly, idempotent, non-destructive, and closed-world behavior, so the baseline is handled. The description earns credit for two things annotations cannot express: the required `payments:read` scope, and the warning that human-authored text arrives in `untrusted_fields` and must be treated as display data rather than instructions — a meaningful prompt-injection safeguard.

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 action and immediately followed by the permission requirement and the safety note. The only wasted phrase is the opening restatement of the title, which duplicates structured data instead of adding to 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?

For a one-parameter read tool with no output schema, the description covers auth and the untrusted-content hazard, which is a reasonable minimum. It still omits what the response contains beyond `untrusted_fields` (status, amount, expiry) and how this tool differs from the near-identically named `get_pay_link`, leaving real ambiguity.

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% and the single `paylink_id` parameter is bare, so the description could have explained whether it is a numeric ID, a token, or a slug. It does not. However, with only one obvious required identifier, the semantic gap is small and the description does not mislead.

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?

"Get a PayLink" names a verb and a resource, but it essentially restates the title and adds no scope detail. Crucially, the sibling list contains both `get_pay_link` and `list_paylinks`, and the description does nothing to distinguish this tool from either, leaving the agent unable to route confidently.

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?

No when-to-use guidance is offered. There is no mention of when this should be chosen over `get_pay_link`, `list_paylinks`, or `get_payment`, and no prerequisites beyond the permission string. The agent must infer selection from tool names alone.

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