fill

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 synthetic event mechanism, notes that it is fast but not equivalent to real typing, and lists missing behaviors (key events, keyboard, autocorrect, composition). It does not cover failure behavior, focus requirements, or what happens with disabled/readonly fields, so it is not fully exhaustive.

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?

Two compact sentences with zero waste. The core behavior and the key limitation are front-loaded, and the alternative tools are named immediately after the caveat.

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 field-fill operation with rich schema coverage, the description covers what the tool does and how it differs from typing tools. Minor behavioral gaps such as focus requirements or error handling are not addressed, but the essential selection context is present.

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 description coverage is high at 83%, so the schema already explains selector, value, page, wait, index, and change. The description adds no parameter-specific details beyond what the structured schema provides, making the baseline 3 appropriate.

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 specific action (set the value of a field) and the exact mechanism used (native setter followed by input and change events). It also distinguishes itself from the typing siblings by naming keyboard_show and type_text, so an agent can choose correctly without opening another schema.

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?

Explicitly says when to use this tool: when the goal is to set a field so the framework notices, and speed matters. It also says when not to use it, because it lacks key events, keyboard interactions, autocorrect, and composition, and names keyboard_show and type_text as the alternatives.

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