List all open tabs and retrieve the active stable page ID within a browser automation session, enabling clear session state inspection and targeted page management without losing context.
List tabs and the active stable page ID for an automation session.
| Name | Required | Description | Default |
|---|---|---|---|
| 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?
Annotations already provide readOnlyHint=true, so safety is known. The description adds the context of 'automation session' and the concept of an 'active stable page ID' as output, but does not disclose error behavior or session requirements.
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 well-structured sentence with no fluff. It front-loads the verb and key outputs, making it easy to parse.
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 low-complexity tool with one optional parameter and no output schema, the description is adequate but not fully complete. It doesn't describe the structure of the returned tab list or what 'stable page ID' means, which could be important for an agent.
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 only parameter (sessionId) has a clear schema description. The tool description adds no additional parameter detail, so the baseline of 3 applies.
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 the specific verb 'List' and clearly identifies the resource: tabs and the active stable page ID for an automation session. It distinguishes from sibling tools like tab_new, tab_select, and tab_close, and also from nex_browser_list which appears more generic.
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 explicit guidance is given on when to use this tool versus alternatives. While it implies usage for inspecting tabs in a session, it does not mention exclusions or compare with sibling listing tools like nex_browser_list.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.