Closes a specific browser tab on a remote mobile device by providing the device serial number and tab ID, returning the API response.
Close one tab.
Args: serialno: The browser device serialno, from list_devices. tab_id: The tab id, from browser_tabs.
Returns: JSON response from the API.
| Name | Required | Description | Default |
|---|---|---|---|
| tab_id | Yes | ||
| serialno | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v0.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the core action and the return value, but does not disclose what happens when closing a tab (e.g., active tab behavior, failure modes, whether the operation is irreversible, or permissions required). For a destructive/state-changing action, this is a notable 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 compact and well-structured: a one-line purpose followed by clear Args and Returns sections. There is minimal waste, and each section is immediately scannable for an agent.
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-required-parameter tool with an output schema, the description is mostly adequate: it identifies the action and tells the agent where to obtain both arguments. However, it lacks usage boundaries and does not mention behavioral caveats or failure cases, which are important for an agent selecting among many browser-tab siblings.
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 0%, so the description must compensate; it does by specifying the source for each parameter: serialno comes from list_devices and tab_id comes from browser_tabs. This adds practical meaning beyond the schema's type/title fields, though it stops short of describing formats or constraints.
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 begins with a specific verb and resource: 'Close one tab.' It clearly distinguishes itself from sibling operations like browser_tab_close_all by emphasizing a single tab, and from navigation/switch operations. An agent can tell exactly what this tool does without needing to inspect schemas.
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 gives no guidance on when to use this tool versus alternatives such as browser_tab_close_all, browser_tab_switch, or browser_tab_close. It only explains where to source the parameters ('from list_devices', 'from browser_tabs'), not the conditions or scenarios in which this tool is the right choice.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.