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

Annotations already signal readOnlyHint=true, so the description adds value by disclosing the base64-encoded return format and the precondition that signing must be complete. This complements the annotations rather than duplicating them, though it does not cover failure modes or auth requirements.

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?

One sentence that front-loads the core action and resource, then states the output format and condition. Every element is necessary and there is no filler.

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 no output schema, the description adequately tells the agent what to pass and what to expect. It could mention behavior when the document is not yet signed or not found, but the stated precondition and return format are sufficient for basic correct invocation.

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 single parameter document_id is fully described in the schema with 'unique document ID', giving 100% schema coverage. The description does not add extra parameter detail, but none is needed given the schema already carries the meaning.

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 clearly states the action (download), the resource (signed/certificated PDF), and the output format (base64-encoded string). It also distinguishes this from the sibling assinafy_download_document by specifying the signed variant, so an agent can tell them apart without inspecting schemas.

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 'after signing is complete' provides clear temporal context for when this tool is appropriate. It does not explicitly name alternatives or exclusion cases, but the wording implies this should be used for the signed version rather than the generic download tool, which is adequate guidance.

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