adb_open_url

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

No annotations exist, so the description carries the full burden of behavioral disclosure. 'Open a URL' implies launching a browser/WebView, but it doesn't state what happens if no browser is installed, whether this requires the screen to be unlocked, whether it opens in a specific default browser, or any error behaviors. For a device-mutation action with zero annotation coverage, this is a significant transparency gap.

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 a single, efficient sentence. The parenthetical example adds user value without bloat. No wasted words, though the use-case note could arguably be considered decoration rather than essential 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?

With no annotations, no output schema, and only 50% parameter schema coverage, this simple tool description is somewhat thin. For a two-parameter tool it's not catastrophic, but it lacks behavioral expectations (what browser opens, whether results are returned), and the url parameter's format is entirely undocumented. It covers the basics but leaves the agent guessing on important operational details.

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 coverage is 50% — only the 'serial' parameter is documented in schema (with a clear 'omit if only one device' instruction). The 'url' parameter has no schema description, and the tool description doesn't add details about URL format (http/https, whether file:// or adb: schemes are valid). The description adds no parameter-level meaning beyond what the schema provides, landing at baseline 3.

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 states the specific verb 'Open a URL on the device' with a clear resource (device/URL). The parenthetical adds a useful use-case example (casting a webpage/dashboard/game to TV). It's distinct enough from siblings like adb_launch (apps) and adb_start_intent (intents), though it doesn't explicitly differentiate from them.

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?

There's no guidance on when to use this vs alternatives like adb_start_intent or adb_launch. The parenthetical hints at a use case (casting to TV) but doesn't clarify when a URL open is preferred over launching an app or sending an intent. No exclusions or prerequisites stated.

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