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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds real behavioral context beyond them: anyone holding the link can sign as that person, and a read-or-draft-only key receives "[redacted]" instead of a usable link. The "Free" note also discloses a pricing trait not visible in annotations.

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?

Four short, front-loaded sentences with no filler; the security warning follows immediately after the purpose. The trailing "Free." fragment is terse to the point of being slightly ambiguous.

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 only two parameters, full annotation coverage, and no output schema, the description supplies the critical missing context: the link is a bearer credential and may be redacted by key scope. Edge cases such as already-signed signers or link expiry are not addressed but are not essential to call it correctly.

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%: request_id is documented in the schema, but email has no description there. The description implies a single signer is targeted ("of one signer", "give it only to them") without explicitly stating that email identifies that signer, so it only partially compensates.

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 ('the signing link of one signer') and disambiguates it from the sibling esign_remind, which emails links rather than returning them. The verb is implied by the tool name/title rather than stated in the description, which keeps it just below 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?

It states the intended use case ("to hand over yourself (in a chat, say)") and gives a constraint ("give it only to them"), plus routes email-based delivery to esign_remind. There is no explicit when-not-to-use beyond the delivery caveat.

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