seleniumbase-mcp

by ileonzin

Overview Schema Source Related Servers Discussions Admin

Python

Local

Manage Tabs

manage_tabs

List, open, switch, and close browser tabs. Get current tab indexes to switch accurately after opening or closing tabs.

Instructions

Manage browser tabs, including opening new ones.

Use this for listing, opening, switching, or closing tabs. Use open_url and manage_history for navigation within the active tab.

Args: action: - "list_tabs": Return each tab's index, URL, and title. Use this to find the tab_index for "switch_to_tab". - "open_new_tab": Open a new tab, optionally navigating to url. - "switch_to_tab": Switch to the tab at tab_index from "list_tabs". - "switch_to_newest_tab": Switch to the newest tab. - "close_active_tab": Close the active tab. This action must be followed by a 'manage_tabs' action that switches to a new tab, such as "switch_to_tab" or "switch_to_newest_tab".

url: URL for "open_new_tab". If not provided, "about:blank" is used.

tab_index: Tab index from "list_tabs" that is only used for the
    "switch_to_tab" action.)

switch_to: If using "open_new_tab", switch to the new tab when True.

Notes: Tab indexes are session-relative and may change after tabs are opened or closed. Use "list_tabs" to get current indexes before switching by index.

Error behavior: If there's an error during any of the tab actions, then @handle_sb_errors will propagate the exception as an error message.

Input Schema

TableJSON Schema

Name	Required	Default
`url`	No
`action`	No	list_tabs
`switch_to`	No
`tab_index`	No

Output Schema

TableJSON Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 15, 2026

TDQS

A4.9/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full disclosure burden and delivers: tab indexes are session-relative and go stale after open/close, close_active_tab has a mandatory follow-up action, open_new_tab falls back to about:blank, and errors propagate via @handle_sb_errors. These are genuinely non-obvious behavioral traps an agent needs to know.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The content is grouped into clear sections (Args, Notes, Error behavior) and front-loaded with the purpose statement. Every sentence earns its place given the tool handles five distinct actions with four parameters; the only blemish is a stray closing parenthesis in the tab_index entry.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Covers action semantics, parameter applicability, defaults, sequencing constraints, index staleness, and error propagation, so an agent can correctly drive every action. It never states a prerequisite such as the browser session needing to be running (start_browser), and edge cases like switching with zero tabs are only handled by the generic error note.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, yet every parameter is semantically documented: action gets per-enum-value behavior, url gets its default behavior, tab_index is scoped to switch_to_tab and sourced from list_tabs, and switch_to is tied to open_new_tab. The Args section fully compensates for the empty schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Opens with a specific verb+resource ('Manage browser tabs') and enumerates the concrete operations: listing, opening, switching, and closing tabs. It further sharpens scope by carving out in-tab navigation as belonging to open_url and manage_history, so an agent can distinguish it from the 22 siblings without inspecting schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives an explicit boundary: use this tool for tab lifecycle operations and open_url/manage_history for navigation within the active tab. It also provides intra-tool routing ('Use this to find the tab_index for switch_to_tab') and a hard sequencing rule for close_active_tab that must be followed by a switch action.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.