browser_set_active_tab

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

With no annotations provided, the description carries the full burden. It discloses a key behavioral trait—that tool calls not specifying a tabId route to the active tab—which is beyond the name and schema. While it doesn't elaborate on side effects (like state changes to the previous tab), this is a simple setter and the core behavior is adequately disclosed.

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 two sentences long, direct, and front-loaded. The first sentence states the core action, and the second explains the routing implication. No filler or redundant content, every sentence earns its place.

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 simple one-parameter tool, the description is complete. It explains what the tool does, the effect on other tool calls, and the intended use case. The schema provides the remaining parameter detail, and no output schema is needed. There are no major gaps in context.

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. The description does not add significant meaning about the tabId parameter beyond what the schema already states. It implies the parameter's role in routing, but the schema already describes it as 'Tab ID to make active.' No extra nuance is provided.

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 clearly states the tool's function with a specific verb and resource: 'Set which bound tab is the agent's active tab.' It also distinguishes itself from sibling tools by explaining the routing behavior (calls without tabId go to the active tab), which differentiates it from tab-management siblings like browser_open_tab or browser_list_tabs.

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 description provides clear context for when to use the tool: 'Use this to switch the agent's focus between bound tabs.' It also explains the effect on other tool calls. However, it does not explicitly mention when not to use it or name alternative tools, so it falls short of the top score.

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