browser_new_isolated_tab

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

With no annotations, the description carries the full burden. It usefully discloses the isolation profile (no shared cookies, clean session storage), which is real behavioral value. It says nothing about lifecycle, though: whether the isolated context persists after the tab closes, how it is referenced later, or whether it becomes the active tab.

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?

One sentence, front-loaded with the action and immediately qualified by the defining property. No filler and nothing buried.

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 one-parameter, no-output-schema tool, the description covers the essential facts: what it opens and how the context differs. The remaining gap is lifecycle/persistence of the isolated context, which an agent might reasonably wonder about, but it is not critical to invoking the tool.

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% for the single 'url' parameter, including its default of about:blank. The description adds no syntax or format guidance beyond that, 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 (Open) and resource (new tab) and immediately scopes it to a 'fresh, completely isolated browser context', which is precisely what separates it from the sibling browser_new_tab. The parenthetical definition of isolation (zero shared cookies, clean session storage) removes any ambiguity about which tool to pick.

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 isolation semantics imply when this tool is appropriate (when you need a clean, cookie-free session), but the description never explicitly says 'use browser_new_tab for a normal tab in the shared context' or names any alternative. Usage must be inferred from the contrast with the sibling name alone.

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