prepare_file

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

Annotations already declare a non-read-only, non-destructive, closed-world operation, so the safety profile is covered. The description adds two useful facts beyond the annotations: no dispatch occurs and a deliveryId is returned, plus that recipients are fixed by local config. It does not say whether prepared copies expire or how long a deliveryId stays valid.

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 clauses: purpose first, then return value and the recipient-config caveat. Nothing is wasted, though the phrasing is terse enough that the filename format question is left silently unanswered.

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 one-parameter tool with no output schema, the description usefully discloses the return value (deliveryId) and the implicit-recipient behavior. It falls short on the file argument's expected form and on what happens to a prepared but unsent copy.

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% for the single required 'file' parameter, which has only min/max length constraints. The description restates it as a 'user-specified file' but gives no indication of whether the value is a path, an ID, or a URL — the one piece of information missing from the 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?

States a specific verb and resource: prepare a copy of a user-specified file, explicitly noting it does not send. The negative clause ('不发送') distinguishes it functionally from the sibling send_file, though it never names that sibling outright.

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?

Implies the prepare-then-send flow by contrasting with sending, and notes the recipient comes from local configuration rather than a parameter. It never states explicitly when to use this versus calling send_file directly, nor what to do with the returned deliveryId.

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