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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered; the description adds real value by confirming no download occurs and no free/quota file is consumed, plus that a multi-item share returns 'pick_required' rather than content. It doesn't mention rate limits or error behavior for bad passwords, keeping it short of a 5.

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 core scope is front-loaded in the first sentence, and the second paragraph is a compact workflow. Some of the prose re-narrates the download tool's contract (pick_required handling) rather than this tool's own behavior, which costs a bit of focus.

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 an output schema present, the description needn't explain return values, and it correctly avoids that while covering the entry paths and the folder-navigation state machine. The only gap is that nothing is said about how `page` relates to long folders beyond the parameter's own note.

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 coverage is 100%, so the baseline is 3, but the description adds relational meaning the schema does not: how `share_id` + `folder_id` combine to open a subfolder, and that `url` is the alternative entry point. It does not explain `page`/`next_page` paging interaction in depth, so not a full 5.

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 and resource ('What is inside a Quark or PikPak share: its folders and files, with sizes') and immediately scopes it against the sibling download tool ('Lists only: downloads nothing'). An agent can distinguish this from download/start_download without opening any 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?

Gives the explicit entry conditions (start with `url`, or continue with `share_id` from a pick_required response or an earlier list_files) and the follow-on action (call `download` with url + share_id + a single file_id). The when-to-use-this-vs-download branching is spelled out in both directions.

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