browser_fill_form

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the mutation nature is conveyed. The description adds no extra behavioral context, such as permission requirements, side effects, or whether existing values are overwritten, but it does not contradict the annotations either. With annotations covering the safety profile, a 3 is appropriate.

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 five-word sentence: 'Fill multiple form fields'. It has zero filler or redundancy and immediately communicates the core purpose, earning a top score for conciseness.

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?

The tool has a complex nested schema that is well-documented, but the description offers no usage context, alternative references, or expected return behavior. With no output schema and minimal description, the context is only moderately complete.

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 has 100% description coverage for the 'fields' parameter and its nested properties (name, type, value, target, element). The description itself adds nothing beyond the schema, so the baseline 3 is warranted.

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 uses the specific verb 'Fill' with resource 'multiple form fields', clearly indicating a batch operation. It's distinguishable from siblings like browser_type (which likely fills a single field) but doesn't explicitly reference those alternatives. Overall, purpose is clear and specific.

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 provides no context on when to choose this tool over browser_type, browser_select_option, browser_click, or other sibling tools. There is also no mention of prerequisites or exclusions, leaving the usage guidance entirely absent.

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