upload_file

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

The description lacks any behavioral disclosure beyond the basic functionality. It does not mention what happens on success/failure, file size limits, whether it replaces previous files, or how it handles invalid selectors. With no annotations, the description should carry the burden but fails to do so.

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 very short (two sentences) and front-loaded with the purpose. However, conciseness is achieved at the expense of important details, which is a trade-off. Still, it is efficient for a simple 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?

Given the tool has 3 required parameters, no output schema, and no annotations, the description is severely incomplete. It does not explain what happens after the file is set, how to verify success, or any error conditions. A minimal description should at least mention that the files are uploaded and the tool returns a success indication.

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. The description adds minimal value by clarifying it works with file input elements, but does not provide additional meaning about parameter formats, constraints, or relationships (e.g., does the selector need to be a file input? what if it is not?).

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 clearly specifies the action: setting files on a file input element. It directly states the verb and resource, and it distinguishes itself from sibling tools like fill_form or click_element by focusing on file uploads via <input type='file'>.

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?

No guidance is provided on when to use this tool versus alternatives. For example, it does not mention that this tool is only for file input elements and not for other form fields, nor does it compare to other upload methods (if any).

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