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

The annotations already declare readOnlyHint=false, idempotentHint=false, and openWorldHint=true, so the non-safe, non-repeatable, external-reaching nature is covered. The description adds one genuinely new caveat ('URL is subject to browser security restrictions'), but says nothing about focus behavior, whether the new tab becomes active, or what happens on load failure.

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 short sentences with zero filler, and the primary purpose is front-loaded ahead of the clarifying exclusion. Nothing could be removed without losing information.

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?

An output schema exists and annotations cover the safety profile, so the description needn't explain return values. But for an 8-parameter tool it leaves the presence of target_id, title, and url_contains — page-selection parameters that look irrelevant to opening a new tab — completely unaddressed, which is a real ambiguity an agent must resolve alone.

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 every parameter is already documented in the schema and the baseline is 3. The description only gestures at the url parameter's constraint and adds no meaning beyond what the schema provides for device, wait, timeout_ms, or endpoint.

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: 'open a specified URL in a new Chromium browser tab on the paired computer.' It also rules out the adjacent behavior with 'This does not navigate an existing tab,' which behaviorally separates it from browser_navigate_url, though it never names that sibling explicitly.

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?

'Use this to open...' gives a clear triggering condition, and the exclusion of existing-tab navigation signals when not to reach for it. However, it stops short of naming the alternative tool (browser_navigate_url or browser_tabs) that the agent should pick instead.

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