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

With no annotations, the description carries the full burden and does supply two real behavioral facts: a hard 128KiB raw-byte chunk limit and idempotent retry on timeout. It omits what happens on an out-of-range or stale offset, whether chunks must arrive sequentially, and any permission/auth requirements — significant gaps for a write operation.

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 short sentences with the size limit and retry rule front-loaded; every clause carries information. The bilingual duplication doubles the token count without adding semantics, which is the only inefficiency.

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 no explanation, and the chunk-size/retry rules are covered. What is missing is the workflow position: how this tool relates to begin_file_upload and finish_file_upload, and what offset value is valid given the current file length — both needed before an agent can call it correctly on a multi-step upload.

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 5 params, so the description must compensate. It clarifies the two operationally tricky ones — 'offset' is a byte offset (按字节偏移) and 'content_base64' is Base64 of at most 128KiB raw bytes — but leaves module_id, file_id, and especially input_name (default "file") completely unexplained.

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: uploading a Base64-encoded chunk, which combined with the required 'offset' param makes clear this appends at a byte offset. It implicitly separates itself from whole-file siblings, but never names begin_file_upload/finish_file_upload/upload_file, so sibling differentiation is only partial.

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 concrete usage rule — retry the same offset/content after a timeout, i.e. the operation is safe to repeat. It does not say when to choose chunked append over upload_file, or whether it must be preceded by begin_file_upload and followed by finish_file_upload; that context is left to inference.

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