Fill multiple form fields in one call. fields is a list of {ref, value} dicts. ref is a CSS selector; value is a string (text) or boolean (checkbox). Saves N round-trips vs calling browser.fill repeatedly.
| Name | Required | Description | Default |
|---|---|---|---|
| fields | Yes | ||
| page_id | Yes | ||
| in_workspace | No | Run this one call in this workspace id instead of the session's. Nothing is stored; other sessions are not affected. |
Changes observed during successful MCP inspections.
Input schema / properties / in_workspaceAdded value: +{
+ "description": "Run this one call in this workspace id instead of the session's. Nothing is stored; other sessions are not affected.",
+ "type": "integer"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the concrete field/ref/value shape and the round-trip rationale, but says nothing about event triggering, clearing existing values, or whether the form is submitted—extra context that would be valuable for a form-filling tool.
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?
Three tight sentences, front-loaded with the action, followed by the parameter shape, then the usage rationale. No filler; every sentence earns its place.
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 browser-automation tool with rich annotations and no output schema, the description covers the non-obvious nested parameter and the efficiency rationale. It omits return behavior and any waiting/event semantics, but the annotations carry the safety profile, so the remaining gap is minor.
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 only 33%, and the nested `fields` items are opaque ({type: object, additionalProperties: true}), so the description's explanation that fields is a list of {ref, value} dicts with ref as a CSS selector and value as string/boolean is essential and compensates well. It does not address page_id, but that parameter is self-evident.
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 multiple form fields in one call') and immediately distinguishes itself from the sibling browser_fill by emphasizing the batch behavior. An agent can tell it apart from browser.fill and browser.type without opening any schema.
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?
'Saves N round-trips vs calling browser.fill repeatedly' names the alternative and implies the condition that favors this tool (multiple fields at once). It gives clear context for preferring this tool but stops short of explicit when-not guidance or mentioning siblings like browser_select_option for dropdowns.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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