form_input

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

With no annotations, the description carries the burden of behavioral disclosure. It does so well by stating that the tool fires input/change events and directly sets values, and by clarifying value handling for select, checkbox/radio, and contenteditable. It does not mention broader side effects like validation or focus behavior, but it covers the key behavior.

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 sentences deliver the core behavior, supported control types, and the key alternative routing. There is no filler or repetition of schema fields.

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 3-parameter tool with no output schema, the description covers what the tool does, how values are interpreted, and when to use an alternative. An agent has enough information to select and invoke it correctly.

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 67%, with `ref` and `tabId` already documented in the schema. The description adds meaningful semantics for `value`, explaining how it maps to different control types: option text/value for select, true/false for checkbox/radio, and content for contenteditable.

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 a specific verb and resource: 'Set a form control's value directly.' It enumerates the exact control types it supports, and the closing note differentiates it from `type`, a sibling tool.

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 explicitly says to prefer `type` for fields that validate on keystrokes, such as card numbers. This gives the agent a clear rule for when not to use `form_input` and names the alternative.

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