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

With no annotations, the description carries the full behavioral burden, and it discloses only the 50MiB maximum. It does not say what happens after the call (e.g., an upload handle coming back), whether the upload is chunked or single-shot, whether a finish step is mandatory, or whether abandoned uploads expire.

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 description is short and front-loads the action, but the bilingual duplication with a bare '/' separator is redundant rather than clarifying, and the English and Chinese halves imply slightly different behaviors (real upload vs. chunked upload).

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?

An output schema exists, so return values need not be explained, but for a lifecycle-initiating tool the description should cover the follow-up calls and the meaning of its three required-ish inputs. Both are absent, leaving an agent unable to sequence this correctly with finish_file_upload or append_file_chunk.

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% across three parameters (module_id, filename, input_name), and the description mentions none of them. An agent gets no idea what module_id refers to or what input_name (default 'file') controls, so the description neither compensates for nor supplements the bare 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 description states a specific verb and resource ('Start a real file upload') and names the transport ('over the existing MCP endpoint'), so an agent can tell this initiates an upload. It does not distinguish itself from siblings such as upload_file, append_file_chunk, or finish_file_upload, and the Chinese fragment ('创建分块上传') reframes it as a chunked-upload creation rather than a plain file upload.

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?

No when-to-use guidance is given: nothing says whether this must be called before append_file_chunk/finish_file_upload, or when upload_file would be the better choice. The only guidance-like content is the 50MiB cap, which is a constraint rather than a selection rule.

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