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

With no annotations at all, the description carries the full burden and does disclose the critical side effect: 'Earlier links for it stop working.' That invalidation behavior is exactly the kind of non-obvious consequence an agent needs before calling. It stops short of covering permissions or what happens when the request is closed/expired.

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?

Two short sentences, zero filler, with the side effect placed after the purpose. The only weakness is that the first sentence is a fragment with no verb, which reads slightly like a label rather than an instruction.

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?

Complexity is low (one required param, one optional), an output schema exists so return values need no explanation, and the key destructive behavior is disclosed. Only the failure mode for a non-open request is left uncovered, which is a minor gap for a tool this simple.

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% — link_days is documented in the schema (default 14, 1–90 range) but signature_request_id has no schema description. The description's 'for an open signature request' partially compensates by implying the ID must reference an open request, but it adds nothing about expiry control or ID sourcing.

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 names a specific resource ('a new signing link') and constrains it to an 'open signature request', which distinguishes it from signatures_request/signatures_get in the sibling list. It is a verbless noun phrase though, so the action (issue/regenerate) is inferred rather than stated.

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?

The phrase 'for an open signature request' implicitly states the prerequisite state needed to call it, which is useful usage context. However, it gives no explicit when-to-use versus alternatives such as signatures_request or signatures_get, and does not say what to do if the request is not open.

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