select_option

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

With no annotations, the description must disclose behavioral traits. It explains that the tool selects by ref and label/value, notes that a dropdown without a ref cannot be selected, and describes the return value. It does not mention any destructive behavior, which is appropriate for a selection tool. Minor omission: no mention of whether the selection triggers navigation or state changes.

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

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

The description is concise and well-structured: a clear one-sentence purpose, a usage warning, and an Args section with parameter explanations. Every sentence adds value without redundancy.

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

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

For a simple 3-parameter tool with an output schema (indicated), the description covers the key constraints (ref must exist in snapshot) and the return format (url and ref count). It is sufficient for correct invocation.

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

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 fully explains each parameter: tab_id (from open_tab), ref (from latest read_tab, must have [eN] ref), value (by visible label or value). This adds essential meaning beyond the schema's property names.

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

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

The description clearly states the tool's purpose: 'Choose an option in a dropdown (a native <select> / combobox)'. It uses a specific verb ('choose') and resource ('option in a dropdown'), and distinguishes from sibling tool 'click' by explicitly stating it is ONLY for <select> dropdowns.

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

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

The description provides explicit when-to-use and when-not-to-use guidance: 'This is ONLY for <select> dropdowns. For radio buttons, checkboxes, links and ordinary buttons, use click instead.' This clearly contrasts with sibling tools.

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