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

Annotations already declare that this is non-read-only, non-destructive, non-idempotent and closed-world. The description adds meaningful behavior beyond that: it returns document_id and a one-use upload_url for a raw-byte PUT, clarifying the upload mechanism and the one-use nature of the URL. Auth and rate-limit details are still absent, but the annotation baseline is well supplemented.

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?

The content is front-loaded and the English sentence is efficient. However, the Chinese sentence repeats the English verbatim, so half the description adds no new information for an English-language agent. The information density is good, but the packaging is redundant.

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?

With no output schema, the description usefully names the return values document_id and upload_url, and annotations cover the safety profile. It still omits the expected follow-up call to finish_document_upload and any upload constraints, leaving the end-to-end workflow incomplete for a multi-step upload tool.

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 merely names all five parameters and notes order_pack_id as optional, which largely restates the schema's property names and required list. It does not explain valid values for kind, the expected sha256 format, or the role of request_id.

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 names a specific action and resource ('Start document upload') and states the registration fields plus outputs. The word 'start' also distinguishes it from the sibling finish_document_upload, so an agent can place it in the lifecycle without opening the schema.

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 implies the initiation workflow by saying the returned upload_url is for a raw-byte PUT, which gives useful context. However, it does not explicitly say when to use this versus alternatives, nor does it state that finish_document_upload should be called afterward, so usage guidance remains implicit.

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