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

With no annotations, the description carries the full responsibility for behavioral context. It clearly states the return value and that no page-source parsing is required, but it does not disclose edge cases like what happens if Chrome is not open, whether multiple tabs are supported, or error behavior. For a simple read-only tool this is adequate but not rich.

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 concise sentences with no filler. The core action and output are stated first, and the value-add over page-source parsing is included without unnecessary 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 single-parameter, read-only utility, the description covers the action, scope, and return value. It lacks error-condition detail and does not explicitly address browser state, but the tool is simple enough that this is a minor gap.

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?

There is only one parameter, udid, and its schema description ('Device serial number (UDID)') fully covers its meaning. Since schema coverage is 100%, the description does not need to add much, and the baseline of 3 is appropriate.

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 uses a specific verb ('Get'), identifies the exact resource ('current URL loaded in Chrome on an Android device'), and states the output ('Returns the URL string'). It also draws a clear contrast with page-source parsing, which helps distinguish it from tools like device_page_source and ios_get_browser_url.

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 phrase 'without needing to parse page source' provides useful context that this tool is the direct way to obtain the URL rather than extracting it from device_page_source. However, it does not explicitly name alternatives or state when not to use it, such as when a different browser or session URL is needed.

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