Switch to a tab

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

The only annotation is readOnlyHint=false, which the description is consistent with, and it adds the important behavioral fact that subsequent input is routed to the active tab. However, it does not say what happens to the previously active tab, whether the window is raised/focused, or how an out-of-range index or stale context id is handled.

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?

Two tight sentences: the action and identifier sources come first, followed by the practical rationale. Nothing is redundant or 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 two-optional-parameter state-change tool with no output schema, this covers what it does, how to identify the tab, and why it matters. Minor gaps around error/failure behavior and focus side effects keep it just short of complete.

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 coverage is 100% and both parameters are already documented, including that index is an alternative to a context id. The description adds only provenance ('from browser_list_tabs'), so the baseline of 3 applies rather than a higher score.

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 ('Make a tab the active one') and even names the underlying API (browsingContext.activate). It is clearly distinguishable from siblings like browser_list_tabs, browser_new_tab, or browser_close_tab.

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?

Gives a concrete use condition — call it before typing or clicking because input goes to the active tab — and points to browser_list_tabs as the source of the context id. It stops short of stating exclusions (e.g. when activation is unnecessary or fails), so it is strong but not fully complete.

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