Lists all open browser tabs in the current session or tab group, so you can inspect and target the right tab for DOM, cookie, or network tasks.
List tabs belonging to the current session (tab group).
| Name | Required | Description | Default |
|---|---|---|---|
| session | No | Per-call session override (does not change the process default) |
Changes observed during successful MCP inspections.
v1.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries full responsibility for behavioral disclosure. It only states the action ('List tabs') without any details about return format, whether it's a read-only operation, error conditions, or session handling. This lack of behavioral information makes the tool's behavior opaque.
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 is front-loaded with the primary action ('List tabs'). It contains no filler, redundant details, or unnecessary categorization. Every word adds value.
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, but without an output schema, the description should clarify what the list contains (e.g., tab IDs, titles, URLs). It also doesn't mention any session-related behavior beyond the scope. The description is sufficient for a minimal understanding but lacks detail about the return value and session edge cases.
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% since the only parameter 'session' has a clear description ('Per-call session override'). The tool description adds no parameter-specific information, but the schema already provides sufficient meaning. Baseline 3 applies because the schema does the heavy lifting.
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 clearly states the tool's function: 'List tabs belonging to the current session (tab group).' The verb 'List' and resource 'tabs' are specific, and the scope ('current session') is explicit. This distinguishes it from sibling tools like wb_find_tab or wb_close_tab.
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 implies use when you need to enumerate tabs, but it does not explicitly state when to use this tool versus alternatives like wb_find_tab, nor does it mention any preconditions or exclusions. Usage context is only implied, not spelled out.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.