close_tab
Closes a specified browser tab by its tab ID, removing unneeded pages from the active Duplex browser session.
Instructions
Close a tab by its id.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| tabId | Yes | Tab id from list_tabs |
Closes a specified browser tab by its tab ID, removing unneeded pages from the active Duplex browser session.
Close a tab by its id.
| Name | Required | Description | Default |
|---|---|---|---|
| tabId | Yes | Tab id from list_tabs |
Changes observed during successful MCP inspections.
v0.2.1Does 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 but says nothing about side effects, permissions, whether closing is reversible, or what happens to tab state.
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 front-loaded sentence with zero waste. For a simple one-parameter tool, this is appropriately sized.
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?
The tool is simple with one required parameter and no output schema, so the description is minimally sufficient for invocation. However, with no annotations and no behavioral detail, it leaves gaps around side effects and error conditions for a mutating action.
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 100% and the single parameter tabId is documented as 'Tab id from list_tabs'. The description merely repeats 'by its id' without adding any format, source, or constraint details beyond the schema.
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 verb and resource: 'Close a tab by its id.' This clearly distinguishes the action from siblings like new_tab, switch_tab, and list_tabs, though it does not explicitly name or contrast those 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?
No guidance is given on when to use this tool versus alternatives, nor any prerequisites or conditions for closing a tab. The intended usage is only implied by the verb 'close'.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.