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 well: it explains preservation of item id/channel/pin, refusal conditions, return shape (item id or job id for uploads over a minute), and security cautions about secrets and owner visibility. This is rich behavioral context beyond the schema.

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 description is front-loaded with the core action and then layers in constraints, return behavior, and visibility context without repetition. Every sentence adds useful information for an agent deciding whether and how to call the tool.

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?

There is no output schema, but the description explains the return value clearly (item id, or a job id for long uploads). Combined with refusal conditions and security notes, it is complete enough for correct invocation.

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 schema already documents all four parameters, including 'title' and 'channel' that the description does not discuss. The description adds slight context that 'path' refers to a file readable by this process, but it largely relies on the schema for parameter meaning.

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 uses a precise verb ('Replace') and resource ('the bytes of a file this agent sent'), and clarifies that the existing item id, channel position, and pin are retained. This distinguishes it from sibling send operations that create new items.

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 clearly states when the tool will refuse: items sent by anyone else, notes, and items with a public share. That gives strong negative guidance, but it does not explicitly name an alternative sibling such as zas_send_file for sending a new file instead of replacing an existing one.

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