lyra-browser

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select_option

Set a dropdown's value, label, or index directly in the browser, firing change events. Enables agents to select options in fields rather than clicking.

Instructions

Choose an option in a <select>, by value, label or index.

Give exactly one of the three. A dropdown is not a click target: this sets the value and fires change, which is what a page listens for. Set submits=true when the choice sends the form (an onchange that posts) — that asks for the permission it needs.

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>"
    },
    "name": "select_option"
  }
}

Input Schema

Name	Required	Description	Default
`index`	No
`label`	No
`value`	No
`reason`	No
`confirm`	No
`submits`	No
`selector`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 3, 2026

TDQS

A4/5.0

Behavior4/5

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

With no annotations, the description carries the burden and does disclose real behavior: it sets the value and fires a change event, and submits=true triggers a permission request. It does not cover failure modes, index base, or what confirm/reason do, leaving gaps.

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

Conciseness4/5

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

Three tight sentences, front-loaded with the core purpose and the exclusivity rule. Efficient, with no filler, though the parenthetical about onchange is slightly wordy.

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

Completeness3/5

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

An output schema exists so return values needn't be described, and the core behavior is covered. However, for a 7-parameter tool with 0% schema coverage, unexplained parameters (selector, reason, confirm) leave the definition short of complete.

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 0%, so the description must compensate. It explains the value/label/index exclusivity and submits, but says nothing about the required selector, reason, or confirm parameters, leaving several of the 7 parameters undocumented.

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?

States a specific verb ('Choose an option') on a specific resource ('<select>'), and explicitly distinguishes itself from the click sibling: 'A dropdown is not a click target.' An agent can route correctly without opening the schema.

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

Usage Guidelines4/5

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

Gives a clear selection rule ('Give exactly one of the three' value/label/index) and the condition for submits=true (an onchange that posts). It also implies when not to use click. No explicit exclusions beyond that, so not a full 5.

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