browser_uploadAttach local files to a page's file input element as if chosen through the file chooser. Use it to automate file uploads in browser-controlled workflows.
Attach local files to a file input element on the page (as if picked via the file chooser).
| Name | Required | Description | Default |
|---|---|---|---|
| files | Yes | Absolute paths of the files to upload | |
| selector | Yes | The file input element (CSS selector or @eN handle) to set files on |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden, and for a page-mutating action it is thin. The 'as if picked via the file chooser' clause is genuinely useful because it tells the agent the native dialog is bypassed and the input's change events fire, but nothing is said about failure modes, permission/visibility requirements, or whether files must exist locally.
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 front-loaded sentence with no filler or repetition. It is efficient, though arguably under-specified rather than optimally tight for an action 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?
For a simple two-parameter tool with 100% schema coverage and no output schema, the description covers the core action adequately. However, given the absence of annotations on a mutating tool, it could say more about what the call changes and when it fails.
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%, so both parameters (files and selector) are already fully documented in the schema, including absolute paths and CSS selector/@eN handle formats. The description adds no parameter detail beyond that, so the baseline of 3 applies.
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 states a specific verb and resource ('Attach local files to a file input element'), and the parenthetical clarifies the mechanism. It does not explicitly differentiate from siblings like browser_fill or browser_type, but the phrase 'file input element' implicitly narrows the scope.
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?
There is no explicit when-to-use guidance, no prerequisites, and no named alternatives. The agent must infer that this is for file-input uploads versus browser_fill/browser_type for text fields, with nothing in the text to confirm that routing decision.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.