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

The annotations already declare the operation read-only and idempotent, so the description adds meaningful operational context beyond them: it specifies that the response is base64-encoded and that an Authorization header with a Bearer token is required. This is useful behavioral information that the annotations do not convey.

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 concise sentences deliver the essential facts in order: the resource, the critical parameter source, the response format, and the authentication requirement. There is no filler, and every sentence adds functional value.

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 single-parameter read-only tool with an output schema and safety annotations, the description covers everything an agent needs to invoke it correctly: the resource, the parameter provenance, the return encoding, and the authentication requirement. No critical information is missing.

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?

The schema has zero description coverage for completed_document_id, but the description fully compensates by explaining where the value comes from and explicitly excluding the original document_id. This gives the agent the exact provenance and a concrete negative example, which is far more than the bare schema provides.

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 a specific verb and resource ('Download the sealed, signed PDF'), making the tool's function immediately clear. It also disambiguates the required input from the original document ID, distinguishing this tool from get_envelope_status and reinforcing its purpose as the retrieval endpoint for the final signed document.

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 description gives clear, actionable usage guidance by stating that the tool requires the completed_document_id from get_envelope_status and explicitly warns against using the original document_id. However, it does not explicitly spell out when to choose this tool over other siblings, so it stops short of a 5.

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