Browser Jet Pilot

browser_fill

Clears and fills input fields or textareas by CSS selector. Sets value directly without change events, suitable for browser automation.

Instructions

Clear and fill an input field or textarea. Does not trigger change events; use browser_type for character-by-character input.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "selector": "<selector>",
      "value": "<value>"
    },
    "name": "browser_fill"
  }
}

Input Schema

Name	Required	Description	Default
`selector`	Yes	CSS selector of the input field
`value`	Yes	The value to fill in

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jun 22, 2026

TDQS

A4.4/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden. It reveals that the tool does not trigger change events, a key behavioral trait. However, it does not mention other behavioral aspects like scroll-into-view, event ordering, or error handling.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with purpose, followed by a critical caveat and alternative. No wasted words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple 2-parameter tool with no output schema, the description covers the essential behavior, key caveat, and sibling relationship. It does not cover edge cases or error states, but is sufficient for basic usage.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with descriptions for both parameters. The description does not add additional meaning beyond what the schema already provides, so baseline score of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool clears and fills an input field or textarea. It distinguishes this tool from sibling 'browser_type' by noting that it does not trigger change events and suggests the alternative for character-by-character input.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly tells when to use this tool (for filling fields quickly) and when not to (when change events are needed, use browser_type). This provides clear guidance compared to sibling tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.