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

readOnlyHint=true already marks it as a safe read. The description adds meaningful operational context: the same Bearer auth as MCP, dedicated transfer URLs that expire and must be re-fetched, files bypassing model base64 context, and preparation not being reportable as a successful upload.

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?

It is short but compressed into semicolon-delimited fragments, and it opens with “登录” rather than the tool’s core purpose. Several clauses describe upload workflow rather than the limits query, reducing front-loading.

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 zero-parameter read-only helper, it supplies relevant auth, expiry, limit-query and upload-success caveats. It stops short of describing the return shape, though no output schema exists; the main workflow context is present.

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?

There are zero parameters, so the schema imposes no semantic burden and no parameter details are needed. Baseline 4 applies.

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 concrete query (“查询格式/字节上限”) but buries it among login, Bearer-auth, URL-expiry, hashing and upload-receipt instructions. The core resource is file-transfer limits, yet there is no explicit differentiation from the sibling prepare_* upload tools.

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 this is called after login and before preparing a file upload, and warns that preparation is not upload success. It does not explicitly say when to use this versus prepare_activity_material_upload, prepare_activity_photo_upload, or prepare_signup_file_upload.

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