Send a document for signature

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

With no annotations, the description carries the full burden and mostly succeeds: it discloses the appended-certificate fallback when fields are omitted, that signing_urls are private and per-signer, and that the send is billable (one unit plus a reported cost). It omits anything about reversibility or how to cancel/void a send, and does not state delivery mechanics (email/text) even though the schema hints at them.

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 sentences, front-loaded with the action and recipient limits, then input form, then field behavior, then return/billing. Every sentence carries distinct information and none restates the title.

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 mutating send with 9 parameters and no output schema, the description is substantively complete: it describes the return payload (document plus per-signer signing_url and cost) and the billing consequence. What is missing is failure/edge behavior for a write operation with no annotation safety profile — e.g., what happens on invalid recipients or how to undo a mistaken send.

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?

At 67% schema coverage, the description adds real value: it contrasts file_url and file_base64 as mutually substitutable input paths, explains the recipient tier caps (25 signers/approvers, 25 view-only, 25 CC) that contextualize the signers array, and clarifies the fields-optional path. It says nothing about sequential, expires_days, title, or filename, leaving those to the schema.

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 first sentence gives a specific verb and resource (upload a PDF and send it for signature) with concrete recipient caps, so the agent knows exactly what the tool produces. It stops short of naming the closest sibling, send_from_template, which is the obvious alternative when the source is a template rather than an uploaded file.

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?

Usage is only implied: the file_url vs file_base64 clause tells the agent how to supply input, and the fields clause explains the consequences of including or omitting field placement. There is no explicit when-to-use-this-vs-alternative guidance against send_from_template or list_templates, nor any noted preconditions beyond the PDF requirement.

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