lyra-browser

Official

Overview Schema Source Related Servers Discussions Admin

open_browser

Launch or focus the visible browser window shared between agent and user. If no browser is installed, return a browser_unavailable notice so the user can install Chrome.

Instructions

Launch (or focus) the visible browser window the user shares with you.

If no browser is installed this returns a browser_unavailable envelope (relay it so the user can install Chrome) rather than failing.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "open_browser"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 3, 2026

TDQS

A3.9/5.0

Behavior4/5

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

With no annotations, the description carries the full burden, and it delivers the most important non-obvious behavior: a missing browser yields a 'browser_unavailable' envelope instead of a failure, which the agent must relay to the user. It stops short of covering consent/permission or whether launching an already-open window triggers a takeover.

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 short, front-loaded sentences with no filler; the primary action comes first and the error-handling caveat second. Every sentence earns its place.

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?

An output schema exists, so return-value detail is unnecessary, and the description adds the key exception case on top. Only minor gaps remain (user-consent or permission implications), acceptable for a zero-parameter launch tool.

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

Parameters4/5

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

The tool takes no parameters, so per the rubric the baseline is 4. There is nothing for the description to clarify beyond what the empty schema already conveys.

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

Purpose4/5

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

States a specific verb and resource: 'Launch (or focus) the visible browser window the user shares with you.' This is clearly distinct from the obvious sibling close_browser, though the description never names a sibling explicitly to differentiate further.

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

Usage Guidelines3/5

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

Usage is implied rather than stated: launching the browser is obviously a prerequisite for the navigate/click/read_page siblings, but the description never says 'use this first' or names alternatives. An agent can infer the ordering but must supply it itself.

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