Open a new browser tab in an existing session, optionally loading a URL, and return its tab ID for switching between tabs.
Open a new browser tab. Returns a tab_id to use with browser_switch_tab.
| Name | Required | Description | Default |
|---|---|---|---|
| url | No | URL to open in the new tab (opens blank tab if omitted) | |
| session_id | Yes | Session ID returned by browser_navigate |
Changes observed during successful MCP inspections.
v2.7.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=true, which cover the mutation and safety profile. The description adds that a tab_id is returned for use with browser_switch_tab, useful context but limited. No additional behavioral traits like permissions or persistence are disclosed.
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?
Two short sentences with zero waste. The core action and return value are front-loaded, making it easy to scan.
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?
Given the tool's simplicity, full schema coverage, and presence of annotations, the description is complete. It covers purpose and return value (compensating for the missing output schema) and links to the follow-up tool.
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%, so parameters are fully documented in the schema. The description adds no further meaning about url or session_id. Baseline 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?
States a specific verb and resource: 'Open a new browser tab.' Clear and distinct from most siblings. However, it doesn't explicitly contrast with browser_navigate, which also involves opening a URL, so the differentiation is only partial.
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?
Mentions that the returned tab_id should be used with browser_switch_tab, implying a workflow. But it offers no explicit when-to-use versus alternatives like browser_navigate, nor any exclusions or prerequisites beyond what the schema shows.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.