ensure_active_tab

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

With no annotations provided, the description fully discloses behavioral traits: it reuses, creates, or launches a browser; it explicitly states it will not close Chrome or terminate the browser process; and it lists platform-specific launch commands. This goes far beyond basic expectations.

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 well-structured and front-loaded with the core purpose. While slightly long due to platform launch details, every sentence earns its place by conveying necessary behavioral guarantees and conditions without redundancy.

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 side-effect-oriented tool with two optional parameters, the description covers all relevant states (active tab, no tabs, no window) and side effects (browser launch, no termination). It lacks explicit return value details, but no output schema exists and the tool's success is largely implied by the conditional logic.

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%, with both 'url' and 'browser' parameters already well-documented. The description adds minimal extra meaning beyond the schema, so a baseline score of 3 is appropriate as the schema carries the heavy lifting.

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 purpose: ensure an active browser tab exists. It specifies the exact verb (ensure) and resource (active tab), and the conditional behavior (reuse existing tab, create new tab, launch browser) distinguishes it from siblings like new_page or navigate_page.

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 this tool by detailing the three scenarios (active tab present, no tabs but browser running, no window) and explicitly notes when the browser will be launched. It does not name alternatives explicitly, but the conditional logic implies when this is the appropriate fallback.

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