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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint false, openWorldHint false), so the bar is lower. The description adds genuinely non-annotation context: the response is base64-encoded and the default artifact is 'original', plus the conditional availability of the signed PDF. It does not mention size limits or error behavior on unavailable artifacts.

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?

Two compact sentences, front-loaded with the action and the encoding, with the conditional caveat second. Minor redundancy with the schema's artifact list costs it the top mark, but nothing is padded.

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?

There is no output schema, and the description does the important compensating work of telling the agent the payload is base64 rather than a URL or binary stream. Combined with the artifact enumeration and the availability caveat, an agent can call this correctly; only edge behavior (unavailable artifact, large-file handling) is unaddressed.

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 100% and the schema already lists the artifact values and marks 'original' as the default, so the description largely repeats structured data. Baseline 3 is appropriate; the description adds no format, ordering, or constraint detail beyond 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?

States a specific verb (download) and resource (document artifact) plus an enumerated set of artifact variants, which is more precise than a generic 'get file'. It implicitly distinguishes itself from assinafy_download_document_page by talking about whole artifacts (original/pades/bundle) rather than pages, but it never names that sibling, so the differentiation is inferred rather than stated.

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 gives one real usage constraint: the signed PDF is only available when the document is certificated and the artifact is listed. That is useful conditional guidance, but it does not say when to prefer this tool over assinafy_download_document_page or assinafy_show_document/get_document, leaving the alternative-selection decision to the agent.

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