browser_fill_form

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

Annotations already indicate destructiveHint=true and readOnlyHint=false, so the tool is known to be a write operation. The description adds no behavioral context beyond the basic action, such as how fields are matched, whether the page must be snapshotted, or side effects. Since no additional context is provided, the score is low.

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 sentence with no wasted words, but it is arguably too terse. It is front-loaded, yet it lacks detail that would make it a 5. Similar to the 'update_drive' example, one efficient sentence earns a 4.

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 handles a complex input schema with multiple field types and nested objects, yet the description gives no information about prerequisites (like needing a snapshot), return behavior, or how it interacts with the page. This is inadequate for a tool with this complexity. The lack of an output schema compounds the issue.

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 100%, so the schema fully documents each parameter (target, name, type, value, element). The description adds no extra semantics beyond the schema. Per the rubric, baseline 3 is appropriate when 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 'Fill multiple form fields' clearly states a specific action (fill) and a resource (form fields), but it does not explicitly distinguish this from sibling tools like browser_type or browser_select_option. The word 'multiple' hints at its scope, but a clearer differentiation would earn a 5.

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 guidance on when to use this tool versus alternatives. It does not mention that it is for filling multiple fields at once or that browser_type/browser_select_option are for single-field interactions. This leaves the agent without clear usage context.

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