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

No annotations are provided, so the description carries the full burden. It discloses that this is a read-only operation (getting a URL) and that it returns a URL string. However, it doesn't mention what happens if Chrome isn't open or no page is loaded (error vs blank), device prerequisites (Chrome must be installed/running), or whether multiple tabs are handled (which URL is returned). These gaps are notable for a device-state-reading tool.

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 sentences, both earning their place: the first states the purpose, the second highlights the efficient benefit (no page-source parsing). It is front-loaded and compact, though the second sentence edges slightly toward marketing language rather than hard functional detail.

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 single-parameter read tool with no output schema, the description provides the core value proposition (returning URL string without parsing source). It could be more complete about edge cases (no Chrome running, multiple tabs), but given the low complexity and that this is a straightforward getter operating within a larger device tool family, it's reasonably complete. There are related siblings (ios_get_browser_url, device_page_source) but the description's differentiation is adequate.

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% (udid is documented as 'Device serial number (UDID)'). With full coverage, baseline is 3, but the description's note about needing the device's UDID to target a specific Android device adds useful context beyond the schema. The description doesn't add format/syntax details but doesn't need to given the single, self-explanatory parameter.

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?

Description uses a specific verb+resource: 'Get the current URL loaded in Chrome on an Android device.' It clearly identifies the resource (Chrome browser on Android) and the action (get URL). It distinguishes well from siblings like device_page_source (full source) and device_navigate_url (navigation), and relates to ios_get_browser_url as the Android counterpart. However, it doesn't explicitly name these siblings as alternatives.

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 notes 'without needing to parse page source,' which implies it's a lighter-weight alternative to device_page_source for URL extraction. It implies the context (when you just need the URL, not the full page source) but doesn't explicitly state when NOT to use it, such as when the target is a different browser or a WebView within an app rather than Chrome.

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