Fill multiple web form fields in one call using selector or ref/value pairs, including checkboxes with booleans and selects with values or arrays.
Fill several fields at once: [{selector|ref, value}]. Checkboxes take a boolean, selects a value or array.
| Name | Required | Description | Default |
|---|---|---|---|
| tab | No | tab id, defaults to current | |
| fields | Yes | ||
| request_timeout | No | Outer page request deadline in milliseconds; defaults to at least 30000 |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description carries the full disclosure burden, yet it never says whether existing values are overwritten, whether it waits for navigation or events, how per-field failures are handled, or whether it is atomic. Only the value-type semantics for checkboxes and selects are supplied.
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 compact sentences with zero filler, front-loading the batch scope and then the payload contract. Nothing is repeated that the schema already states.
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?
The payload contract and value typing are covered, which is the core need for a form-fill call, and no output schema exists to explain. However, with no annotations and a mutating action, the absence of any note on overwrite, timing, or failure behavior leaves a real gap for an agent deciding how to call it safely.
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 67%, and the description adds real meaning the schema cannot express: the {selector|ref, value} pairing plus type rules that checkboxes take booleans and selects take a value or array. It leaves 'tab' and 'request_timeout' to their schema descriptions, which is acceptable given they are documented there.
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 and resource ('fill several fields at once') and shows the batch payload shape, which distinguishes it in spirit from the single-field 'fill'/'type' siblings. It never names those siblings explicitly, so the differentiation is implicit rather than stated.
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?
'Fill several fields at once' implies the batch case is the trigger, which is a usable cue for choosing this over 'fill'/'type'/'select'/'check'. There is no explicit when-not guidance or named alternative, leaving the agent to infer the boundary.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.