browser_upload_fileUpload a local file to a web page by targeting the file input or its trigger button, enabling browser automation for file submissions.
Upload a local file. Ref may point to the file input or its trigger button.
| Name | Required | Description | Default |
|---|---|---|---|
| ref | Yes | ||
| tab | No | ||
| path | Yes | ||
| session | No | default |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v2.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must carry the behavioral burden. It only says 'Upload a local file' without disclosing side effects, error conditions, or any requirements (e.g., whether the path must exist, what happens on failure). This is insufficient for a mutating action.
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 extremely short and front-loaded with the core action, which is concise. However, it's under-specified to the point of being unhelpful, sacrificing necessary detail for brevity.
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 tool with 4 parameters (2 required), no parameter documentation, and no behavioral details, the description is inadequate. Even though an output schema exists, the agent cannot confidently invoke this tool without knowing what 'path' expects or how errors are handled.
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 0%, so the description must compensate. It explains 'ref' (points to file input or trigger button) but leaves 'path', 'tab', and 'session' unexplained. The description adds minimal value for the other three parameters.
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 tool uploads a local file, and mentions 'Ref' can point to the file input or trigger button. It distinguishes itself from siblings like browser_fill and browser_click because it's the only upload tool, though it doesn't explicitly name alternatives.
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 vs alternatives, prerequisites (e.g., file existence, element visibility), or exclusions. The intended context is implied but not stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.