Open a new browser tab and optionally navigate to a URL. Use a session ID to select the target browser session.
Open a new tab and optionally navigate it.
| Name | Required | Description | Default |
|---|---|---|---|
| url | No | ||
| sessionId | No | Optional session ID; defaults to this MCP client active session |
Changes observed during successful MCP inspections.
v2026.8.14Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It only states the core action without disclosing side effects such as whether the new tab becomes active, return values, or session prerequisites.
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 concise sentence that front-loads the primary action, with no wasted words.
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 tool with two optional parameters and no output schema, the description conveys the core behavior but lacks details about return values or session interactions. It is minimally adequate given the simplicity.
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?
The schema already documents sessionId with a description, and the description adds meaning for the url parameter by indicating it is an optional navigation target. However, it does not specify URL format or behavior when omitted.
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 ('Open') and resource ('new tab'), and adds the optional navigation scope, clearly distinguishing it from navigation-only tools like nex_browser_navigate.
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?
Usage context is implied: use when you need a new tab. However, there is no explicit guidance on when to prefer this over alternatives like nex_browser_open or nex_browser_navigate.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.