Browser Type

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

No annotations are provided, so the description carries the full behavioral burden. It discloses targeting behavior for iframes and shadow DOM and implies it does not submit forms by itself, but it does not explain whether typing replaces or appends existing text, whether input/change events fire, or what errors or waiting behavior to expect.

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 front-loaded with the core action and then adds practical examples, sibling interaction, and targeting edge cases. The examples and iframe/shadow DOM notes are relevant and earn their place without excessive repetition.

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 5-parameter browser action with no annotations and no output schema, the description covers purpose, common use cases, examples, iframe targeting, shadow DOM targeting, and form submission handoff. It still omits mutation details such as text replacement versus append, event firing, and return/error 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?

Schema description coverage is 100%, so the baseline is 3, but the description adds useful examples for selector and text and clarifies that shadow DOM selectors do not need frameIndex. It does not add meaning for mode or sessionId beyond what the schema already provides.

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 states a specific verb and resource: type text into input fields, textareas, search bars, or contenteditable elements. It distinguishes related behavior by explaining that it fills fields and should be combined with browser_click to submit forms, and it calls out iframe and shadow DOM targeting.

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?

It gives clear usage contexts such as filling out forms, entering search queries, writing messages, and typing login credentials. It also explains how to combine with browser_click and how to target iframes or shadow DOM, but it does not explicitly state when to prefer alternatives like browser_form_fill or browser_keyboard.

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