zas_replace_file

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

With no annotations, the description carries the full burden and does so richly: refusals (foreign items, notes, publicly shared items), the dual return shape (item id, or job id for uploads over a minute), and the owner-visible agent mark across devices. These are exactly the operational facts an agent needs before invoking a mutation tool.

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?

Four sentences, each front-loaded with a distinct fact: what it does, what it refuses, what it returns, and the visibility/safety caveat. No filler and nothing repeated.

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 4-parameter mutation tool with no annotations and no output schema, the description supplies the missing pieces an agent needs: refusal conditions, return value semantics including the async job-id case, and a safety warning. Nothing material is left unstated.

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 100%, so id, path, title, and channel are already documented in the schema. The description reinforces that the item id must match an item the agent itself sent and that channel is optional only with a single channel, but adds no syntax or format detail beyond the schema. Baseline 3 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?

States a precise verb+resource: replacing the bytes of a file the agent previously sent, from a local path. It also names the preserved attributes (item id, channel position, pin), which distinguishes it from zas_edit_item (metadata edits) and zas_send_file (new item). An agent can differentiate it from siblings 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?

Clearly delineates when this tool refuses to act: items sent by anyone else, notes, and items with a public share, plus a pre-send caution about secrets/keys/credentials. It does not, however, explicitly name the alternative tools (e.g. zas_edit_item for metadata, zas_send_file for new uploads), leaving the agent to infer the boundary from the refusal list.

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