browser_upload_file

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

With no annotations, the description carries the full burden. The 'via CDP' phrase usefully implies no native file-picker dialog appears and that paths are resolved on the browser host, but it says nothing about whether files must already exist, permissions on local paths, whether change events fire, or failure behavior for a mutation-like operation.

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?

A single well-formed sentence with the action and target front-loaded and zero filler. It is efficient, though the extreme brevity leaves no room for the operational caveats the tool would benefit from.

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 two-parameter tool with full schema coverage, no annotations, and no output schema, the description is minimally adequate. It omits what success/failure looks like and the preconditions for the target element and file paths, so an agent has gaps to fill.

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% for both parameters ('List of absolute file paths to upload', 'CSS selector for the file input'), so the schema already does the work. The description's 'one or more files' merely restates the array type and adds no format or constraint detail beyond 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 (upload) and resource (files to an <input type='file'> element), and the 'via CDP' clause distinguishes it from OS-level file dialogs. It doesn't explicitly name a sibling or contrast itself with browser_fill, but the action is unambiguous.

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 when-to-use guidance, no prerequisites (e.g., the input element must already exist in the DOM), and no mention of alternatives such as browser_click/browser_handle_dialog for triggering native file pickers. The agent must infer the context entirely.

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