Select option

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

With no annotations, the description carries the full burden and does well: it discloses the interaction mechanism (focuses the dropdown, drives it with arrow keys on Windows/Linux and first-letter typing on macOS), that real events reach the page, and states the failure behavior ('If nothing matches, lists the available options'). It stops short of runtime traits such as timeouts, waiting behavior, or whether a selection triggers navigation.

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?

Three sentences, front-loaded with the action, then the mechanism, then the failure mode — nothing is padding. The platform-specific keystroke parenthetical is slightly more detail than an agent needs to select the tool, which keeps it just under a 5.

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 tool with 8 parameters, 3 required, and no output schema, the description covers the core action, its side effects on the page, and the error/no-match path. The auxiliary parameters (slot, tab, read, agent, summary, multiSlot) rely entirely on the schema to explain themselves, so the description is adequate rather than fully complete.

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?

Schema coverage is 100%, so the baseline is 3. The description goes beyond the schema's bare 'Option value or text' by adding 'partial match OK' and clarifying that either the value or the visible text is accepted, which is real semantic value for the required option parameter. The other seven parameters are left entirely to the schema.

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?

States a concrete verb and resource — 'Picks an option in a <select> dropdown' — and even specifies the matching modes (value or visible text, partial match). This is unambiguous on its own, but it never names the sibling it is most confusable with (browser_tab_select) to make the disambiguation explicit.

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?

Usage is implied by the purpose statement (use this to choose a value inside a select element rather than clicking), and the description hints that this is preferable because 'no list popup opens'. However, it never states when NOT to use it (e.g. custom non-native dropdowns) nor names alternatives such as browser_click or browser_fill.

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