browser_fill_form

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

With no annotations, the description must disclose behavioral traits. It only reveals that filling happens 'in order', but does not mention whether it clears existing values, triggers events, waits for element stability, or any side effects. This is a significant gap for a mutation tool.

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, so it's brief and free of padding. However, its brevity comes at the cost of required elaboration, making it under-specified rather than efficiently concise.

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?

For a tool with three parameters, one nested array, no annotations, and no output schema, this description is too sparse. It doesn't mention what happens after filling (e.g., whether the form is submitted), how it handles errors, or what the response looks like. As a result, an agent cannot fully anticipate the tool's behavior.

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 covers 67% of top-level parameters with descriptions, and the 'fields' parameter has no top-level description. The description does not clarify the structure of the array items (beyond the schema's nested descriptions) nor the meaning of 'value' or how 'target' resolves. It adds no new semantic information.

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 verb 'fill' with a clear resource ('form controls') and adds a sequencing qualifier ('in order'), making it distinct from siblings like 'browser_type' or 'browser_select_option' which target specific controls. However, it doesn't elaborate on what constitutes a form control or how it handles mixed control types.

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 prefer this tool over alternatives such as browser_type for single fields or browser_select_option for dropdowns. The description only states what it does, not the scenarios or prerequisites.

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