Opens a browser tab, optionally at a specified URL, and returns its tab ID so you can switch to it when needed.
Open a new tab, optionally at a URL. Returns its id; use switch_tab to make it current.
| Name | Required | Description | Default |
|---|---|---|---|
| tab | No | tab id, defaults to current | |
| url | No | ||
| timeout | No |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It usefully discloses that the tab is not made current and that an id is returned, but says nothing about timeout behavior, whether the call blocks until page load, or failure behavior for invalid URLs. Solid but incomplete for a mutation tool.
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 tight sentences, front-loaded with the action and followed by the return value and the follow-up call. Zero filler.
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?
Return value is covered despite no output schema, and the switch_tab follow-up is noted. However, with two of three parameters undocumented and no annotations, the description leaves timeout and tab-selection behavior unexplained.
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 only 33% — only 'tab' has a description. The description adds that the URL is optional (already implied by required=[]) but never explains the 'timeout' semantics or what 'tab' means when creating a new tab. It does not compensate for the coverage gap.
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 tab') plus the URL option, which clearly separates it from switch_tab / close_tab / tabs siblings. It stops short of 5 because it doesn't clarify how the 'tab' parameter relates to opening a *new* 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?
Explicitly routes the agent: opening does not focus the tab, and switch_tab must be called to make it current. That is actionable sequencing guidance. No explicit exclusions or prerequisites (e.g., browser session state) are given.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.