wb_upload

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

No annotations are provided, so the description carries the full burden. It discloses path format restrictions and the requirement that the input element already be present. However, it doesn't mention what happens if the selector doesn't match, whether change/input events are fired, or error behavior—leaving some transparency gaps.

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?

Two sentences, front-loaded with the verb and resource, and every sentence adds essential information. No fluff or repetition.

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's simplicity and no output schema, the description covers key constraints (path format and page condition) and the input schema defines required parameters. It's reasonably complete for a straightforward file upload tool, though it could explain error handling or interaction with dynamic pages.

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 covers 67% with descriptions for files and session, but selector lacks description. The description adds meaning beyond the schema by clarifying that files must be absolute local paths, not URLs, and that the page must already have the input element (which informs how selector should be used). This adds concrete value.

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 states the action ('Set files on a file input element') and specifies the resource type. It distinguishes itself from sibling tools like wb_fill and wb_click by focusing exclusively on file inputs, and immediately adds critical constraints (absolute local paths, existing input element).

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?

Provides explicit conditions for use: files must be absolute local paths (not http/data URLs) and the page must already show an <input type=file>. This gives clear context and prerequisites. It doesn't explicitly name alternatives, but the constraints and sibling list imply that this is the file-specific tool.

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