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

Annotations only provide idempotentHint=true, readOnlyHint=false, and destructiveHint=false. The description adds crucial behavior: it does not re-send, each URL/token authenticates as that recipient, requires envelopes:send rather than envelopes:read, and returns ordinary agent-link URLs valid for embedding. No contradiction with 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?

Every sentence adds useful information: purpose, output shape, permissions, embedding behavior, and optional parameter. The most important operational fact is front-loaded, and there is no fluff or repetition.

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?

The description is thorough for a moderately complex tool: it includes the output shape, authorization requirement, iframe compatibility, and the distinction from agent-link. The only real gap is that document_id is not explicitly tied to the envelope identifier, which would make the call fully unambiguous.

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 0%, so the description must compensate. It explains recipient_email well ('keeps one recipient') but does not explicitly define document_id or connect it to the envelope ID returned by send_envelope/send_draft/send_from_template. Since there are only two parameters, one is explained well and the other is only implied.

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 'Fetch recipient signing URLs for an already-sent envelope without sending again,' which names a specific verb, resource, and scope. It clearly distinguishes this from sibling send tools by emphasizing the envelope is already sent.

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 key condition (already-sent envelope), the permission class (envelopes:send, not envelopes:read), and what the tool does not do (does not mint a second URL scheme, does not replace agent-link). It does not explicitly say 'use send_envelope instead when you need to send,' but the context leaves little ambiguity.

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