browser_fill_form

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

Annotations already mark the tool as destructive and non-read-only, so the description is not required to restate that. But it adds no behavioral context beyond 'fill' – nothing about side effects, whether it replaces values, whether it can trigger validation, or what happens on error. The description carries none of the additional burden normally expected for a mutating tool.

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 extremely concise, containing no fluff or wasted words. However, it is perhaps too sparse to be genuinely helpful, but for a simple one-liner it is well-structured and front-loaded.

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?

Despite the detailed schema, the description lacks context on when and how to use this tool. It does not mention that it handles multiple field types, that it requires a snapshot reference, or whether it is appropriate for a submission flow. An agent would need to inspect the schema and infer usage, leading to an incomplete picture.

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 100% coverage, with every parameter documented (name, type, value, target, element). The description itself adds no information about parameters; it merely restates the purpose. Baseline of 3 is appropriate because the schema does the heavy lifting.

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 states a clear verb ('Fill') and a resource ('multiple form fields'), which distinguishes it from single-field tools like browser_type or browser_select_option. However, it is minimal and does not describe the exact behavior beyond the basic action, so it does not fully differentiate among the many browser siblings.

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?

There is no guidance on when to use this tool versus alternatives such as browser_type for single fields or browser_select_option for dropdowns. No context is given about prerequisites, such as needing a snapshot or being on a form page.

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