fill

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

With no annotations, the description must disclose behavioral traits. It only says 'Fill an input' but does not specify key behaviors: whether existing content is cleared, what events are triggered, whether the element must be visible, or what the confirm_dangerous parameter implies. The tool could have destructive side effects (as hinted by confirm_dangerous), but the description is silent on this.

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 concise at one sentence, but lacks structure. It could list the fields or add a note about confirm_dangerous. While brevity is valued, it omits critical information, making it borderline under-specified.

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 5 parameters, no annotations, and an output schema, the description is incomplete. It does not explain the return value (output schema exists, but description need not) nor the behavior of confirm_dangerous. The tool has safety implications that are not addressed, leaving gaps in agent understanding.

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 0%, so the description must compensate. It mentions three param names (label, selector, placeholder) but does not explain their semantics (e.g., does label match aria-label or associated text?). The required 'value' and the boolean 'confirm_dangerous' are completely unexplained. The description adds minimal meaning 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 clearly states the verb 'Fill', the resource 'input', and the three methods (by label, CSS selector, or placeholder). This differentiates from sibling tools like click or select, which perform different actions. The purpose is specific and unambiguous.

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 is provided on when to use this tool versus alternatives such as click or select. There is no mention of prerequisites, contextual cues, or when not to use it. The description assumes the agent will infer usage from the tool name alone.

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