browser_fill

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

No annotations are provided, so the description must convey all behavioral traits. It fails to disclose side effects (e.g., whether the field is cleared before filling, whether events are triggered), error handling (e.g., what happens if the field doesn't exist), or any constraints on the value.

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 very short (one sentence), which is concise, but it omits essential details. It is neither front-loaded nor structured; it simply states the bare action.

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 three required parameters, no schema descriptions, no annotations, and an output schema that is not described, the description is severely incomplete. It does not explain how to get session_id, what the output means, or how to handle errors.

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?

With 0% schema description coverage, the description adds no meaning to the parameters. It mentions 'CSS selector' but does not explain session_id role or value format. The schema itself has no descriptions, so the agent gets no parameter guidance.

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?

Description clearly states the action (fill), the target (form field), and the method (CSS selector). It is easily distinguished from sibling tools like browser_click or browser_navigate. However, it does not specify what types of values are supported (e.g., text, numbers).

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?

No guidance on when to use this tool versus alternatives, such as when to use browser_click for interactive elements. No prerequisites or error conditions are mentioned.

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