mobile_open_urlOpens a specified URL in the browser on a chosen mobile device. Provide a device identifier and URL to launch web content on Android or iOS simulators, emulators, or real devices.
Open a URL in browser on device
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | The URL to open | |
| device | Yes | The device identifier to use. Use mobile_list_available_devices to find which devices are available to you. |
Changes observed during successful MCP inspections.
v0.0.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate this is a mutating, non-destructive, open-world operation. The description adds the useful detail that the URL is opened 'in browser,' but does not disclose side effects like switching the foreground app or requiring the device to be unlocked.
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 short sentence that is immediately understandable and front-loaded. There is no wasted text.
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 two-parameter tool with fully documented schema and no output schema, the description is nearly complete. A note about expected behavior after opening the URL, such as switching to the browser app, would make it fully complete.
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 'device' already documented. The description adds no parameter-specific detail beyond what the schema provides, so 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 states a specific action ('Open a URL'), the resource ('URL'), and the context ('in browser on device'). This clearly distinguishes it from siblings like mobile_launch_app, which launch apps rather than URLs.
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 use case is implied by the description: use this when a URL needs to be opened in a browser on a device. However, it does not explicitly state when to prefer this over alternatives such as mobile_launch_app or when not to use it.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.