fill

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

No annotations are provided, and the description does not disclose behavioral details such as what happens if the selector is invalid, whether the field is cleared before filling, or if it works on non-text inputs. The description carries the full burden but adds minimal transparency.

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 short (4 words), which indicates under-specification rather than conciseness. While it is front-loaded with the purpose, it fails to provide necessary context, making it insufficient.

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 having an output schema (not shown), the description does not explain return values. Given the simplicity of the tool, more context (e.g., success indication, errors) would be expected. The description is incomplete for effective use.

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 schema description coverage is 0%, and the description adds no meaning beyond the parameter names ('selector', 'text'). It does not explain the format of selectors, expected input types, or behavior for the parameters.

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 an input field' clearly states the action and resource. It is a specific verb+resource combination that distinguishes it from sibling tools like 'click' or 'navigate', but does not explicitly differentiate from similar tools like 'fill_by_label' or 'type_text'.

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 explicit guidance on when to use this tool versus alternatives is provided. The use case is implied (filling input fields), but there are no exclusions or context about when not to use it.

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