browser_type

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

Annotations cover safety (readOnlyHint=false, idempotentHint=true, destructiveHint=false), and the description goes well beyond them: no key events are dispatched, Enter-to-submit won't trigger, failure mode and timing (~6 s, 'no preview pane running'), and a credential-page refusal requiring user consent. That is unusually rich behavioral disclosure.

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?

Four tight sentences, front-loaded with the action and its input/change behavior, then caveats, then prerequisites. Every sentence carries actionable information; nothing is padding.

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?

With no output schema, the description still covers the return values ('typed' or 'not found'), the failure mode and latency, the prerequisites, and the auth gate for credential pages. Nothing an agent needs to invoke this correctly is missing.

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 both `selector` and `text` are already documented in the schema, including the replace-not-append and empty-string-clears semantics. The description restates the replacement behavior but adds no new parameter-level syntax or formatting detail, so the baseline 3 applies.

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?

States a specific verb and resource ('Fill a form field in the preview') and enumerates the exact mechanics: focuses the field, replaces its whole value with `text`, fires input and change. This is clearly separable from siblings like browser_click (which sends real input) and browser_eval (which runs arbitrary code).

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?

Explicitly states when this tool is the wrong choice ('No key events are sent, so keydown handlers and Enter-to-submit don't fire — click the submit button instead'), routing the agent to browser_click for submission. It also names the prerequisite (browser preview open with agent access) and the refusing condition for credential pages.

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