browser_fill_form

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only says 'fill' without detailing side effects, whether fields are validated, what happens on failure, or whether any events are triggered. This is insufficient for an action tool that mutates a webpage.

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 a single, focused sentence that conveys the core purpose without any fluff or repetition. It is appropriately sized for its simplicity.

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?

Given no annotations, no output schema, and a parameter that references 'page snapshot', the description omits critical context like prerequisites (obtaining refs via browser_snapshot), error behavior, and whether the operation is atomic. This leaves the agent with insufficient information to use the tool correctly in complex scenarios.

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 low (the top-level 'fields' parameter has no description), so the description should compensate. It only says 'form fields' without explaining that each field requires a 'ref' from the page snapshot or how the value is applied. The nested schema has useful descriptions, but the description itself adds minimal value beyond 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?

The description 'Fill multiple form fields in one call' clearly states a specific verb and resource, and the phrase 'multiple form fields' distinguishes it from single-field tools like browser_type. It is unambiguous and directly explains what the tool does.

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 implies usage for filling multiple fields at once, which hints at a batching scenario, but it does not explicitly mention alternatives or when not to use it. Sibling tools like browser_type and browser_select_option exist, and the description doesn't contrast with them, leaving the when-to-use guidance somewhat implicit.

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