fill_formFill multiple form fields in one browser call using refs or selectors for text, select, checkbox, or radio inputs, then optionally submit the form.
Fill multiple fields in one call and optionally submit. Each field may use ref or selector; type can be "text", "select", "checkbox" or "radio".
| Name | Required | Description | Default |
|---|---|---|---|
| tabId | No | ||
| fields | Yes | ||
| submit | No | ||
| timeout | No | ||
| trusted | No | ||
| continueOnError | No |
Changes observed during successful MCP inspections.
v0.1.3Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden and discloses little: it does not explain that 'submit' triggers form submission (a consequential side effect), what 'trusted' changes about event synthesis, or how 'continueOnError' alters failure handling. Only field addressing and type values are covered.
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 the core capability front-loaded and no filler. The second sentence partially restates the schema's enum, but with 0% schema coverage that restatement still carries information.
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 6-parameter tool with a deeply nested fields array, no annotations, and no output schema, the description omits too much: submission semantics, error-handling behavior, timeouts, and trusted-event behavior are all unaddressed. An agent can call it, but not confidently for anything beyond the simplest text fill.
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% and the description clarifies only two things: fields accept ref or selector, and type is one of four enum values. The other top-level parameters (tabId, submit, timeout, trusted, continueOnError) and nested options (clear, delay, index, label, value, values, checked, frameId, pressEnter) remain unexplained in both schema and description.
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 fields'), and the phrase 'in one call' implicitly contrasts with the single-field type/select siblings. It does not name an alternative tool outright, so it stops short of a 5.
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?
Usage is only implied: an agent can infer this is the batched alternative to repeated type/select calls, but the description never states when to prefer it or when a single-field tool is more appropriate. No exclusions or prerequisites are given.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.