seleniumbase-mcp

by ileonzin

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Python

Local

Select Option

select_option

Choose an option from a native HTML select dropdown by visible text, value, or index.

Instructions

Select an option from an HTML dropdown.

Args: dropdown_selector: CSS selector identifying the element.

value: The option's visible text, its HTML value attribute, or its
    0-based index, depending on by.

by:
    - "text": Match the option's visible text.
    - "value": Match the option's HTML value attribute.
    - "index": Match the option's 0-based position. Both integer and
      numeric-string values are accepted.

Raises: An error when the dropdown or requested option cannot be found.

This tool is for native elements. For custom JavaScript dropdowns made from div/button/list elements, use click_element or other element-interaction tools instead.

Input Schema

TableJSON Schema

Name	Required	Default
`by`	No	text
`value`	Yes
`dropdown_selector`	Yes

Output Schema

TableJSON Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 15, 2026

TDQS

A4.8/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=false and destructiveHint=false, but the description adds valuable context: it mentions that an error is raised when the dropdown or option cannot be found, and it explains the flexibility of the 'value' parameter. While it doesn't detail side effects like triggering change events, it provides enough behavioral transparency beyond the annotations. No contradiction exists.

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?

The description is well-structured and concise. It starts with a clear purpose, then lists parameters in a readable format, followed by error behavior and a usage note. Every sentence serves a purpose, no fluff, and the information is front-loaded.

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

Completeness5/5

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

The tool has an output schema (though not shown, context signals indicate it exists), and the description covers all essential aspects: what the tool does, how to use each parameter, error behavior, and when to use alternatives. Nothing critical is missing for correct invocation.

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

Parameters5/5

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

The input schema has 0% description coverage, so the description carries the full burden of parameter explanation. It thoroughly defines 'dropdown_selector', 'value' (including accepted types), and 'by' (with all three modes: text, value, index). This substantially adds meaning beyond the bare schema, fully compensating for the lack of schema descriptions.

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's function: 'Select an option from an HTML <select> dropdown.' It specifies the resource (native <select> elements) and explicitly distinguishes it from custom JavaScript dropdowns, naming the alternative (click_element). This makes the tool's purpose unambiguous and differentiates it from sibling tools.

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?

The description provides explicit usage guidance: 'This tool is for native <select> elements. For custom JavaScript dropdowns made from div/button/list elements, use click_element or other element-interaction tools instead.' This directly tells the agent when to use this tool and when not, referencing a specific alternative, which is exemplary.

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