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select_option

Select an option from a native select or custom dropdown using a CSS selector, value, label, or index. Enumerate available options by omitting selection criteria.

Instructions

Select an option from a native or custom ARIA/portal dropdown. Identify the target control via CSS selector or @eN ref, then specify which option to select by its value attribute, visible label text, or zero-based index. Omit value, label, and index to open the dropdown, enumerate the currently available options, and return them without selecting. Returns post-action page_state showing any page changes triggered by the selection (e.g. dependent dropdowns updating).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
indexNoZero-based index of the <option> to select (0 = first option). Use when value/label are unknown.
labelNoThe visible text of the option to select (e.g. "United States", "Medium"). Use when you know the display text.
valueNoThe value attribute of the option to select (e.g. "us", "medium"). For custom dropdowns without exposed values, this is matched against visible option text.
widenNoWhen true, return the full-page diff instead of scoping to the interacted container. Default: false.
selectorYesCSS selector or @eN ref targeting the native select or custom dropdown trigger (e.g. "@e4", "select#country", "button[role='combobox']").
Behavior5/5

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

Despite no annotations, the description fully discloses behavior: selection triggers page changes, returns page_state, fallback matching for custom dropdowns, and widen parameter effect.

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?

Four succinct sentences, front-loaded with purpose, no redundant information. Efficiently structured.

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?

Covers return value, alternative usage modes, and parameter options. Missing error handling details but sufficient for common use cases given no output schema.

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?

Schema coverage is 100%, so baseline 3. The description adds value by explaining the enumeration mode when all optional params omitted, which goes beyond individual parameter 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 it selects an option from a native select or custom dropdown, and also describes the enumeration behavior. It distinguishes from sibling tools like click and fill_form.

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?

Explains when to use each parameter (value, label, index) and the enumeration use case. Does not explicitly exclude other tools but provides clear context.

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

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