download_file

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

With no annotations, the description carries the full load and it does so: it states the operation is a read of live data, enumerates the four returned fields, and warns that large downloads can fill the context window. This goes beyond a bare 'download' and accurately sets expectations about payload size and side effects.

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?

Three compact sentences front-load the core action and return shape, then end with a practical caveat and routing hint. There is no filler or repetition of schema fields beyond what is useful.

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?

Despite having no output schema, the description enumerates the return fields (mime_type, size_bytes, is_image, content_base64), states the supported file types and ~1MB limit, and warns about context-window risk. For a single-parameter read tool, this gives an agent enough behavioral and return information to invoke it correctly.

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?

The schema already fully documents file_id as 'Rentvine fileID', so the description doesn't need to add parameter-level semantics. The description adds minimal context by tying file_id to the file being downloaded, but it adds no format, constraints, or allowed values beyond the schema. Schema coverage is 100%, so baseline 3 is appropriate.

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 the exact operation ('Download a Rentvine file as base64') and clarifies it is a live read, making the action unambiguous. It also contrasts with list_attachments by describing what this tool returns versus what that workflow step is for. However, it does not explicitly differentiate itself from the similarly named sibling get_file, so the distinction is clear but not fully spelled out.

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 concrete guidance on when to pause before using it: if the file may be large, the agent should call list_attachments first to check file_size. This is an explicit condition and an explicit alternative, which helps an agent decide between tools. The ~1MB mention reinforces the boundary.

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