browser_open_tabOpens an HTTP, HTTPS, file, or about:blank URL in a connected Chrome tab, with an option to make the tab active.
Open an HTTP, HTTPS, file, or about:blank URL in Chrome.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | ||
| active | No | ||
| browser | No | Which connected Chrome to use: an instanceId or label from browser_list_instances. Required when more than one browser is connected; session-based tools infer it from their sessionId. |
Changes observed during successful MCP inspections.
v0.9.1Input schema / properties / browserAdded value: +{
+ "description": "Which connected Chrome to use: an instanceId or label from browser_list_instances. Required when more than one browser is connected; session-based tools infer it from their sessionId.",
+ "maxLength": 100,
+ "minLength": 1,
+ "type": "string"
+}v0.6.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It notes the accepted URL schemes but says nothing about whether a new tab is created, whether it becomes focused, how the 'active' flag behaves, or what happens on a malformed URL — significant gaps for a browser-mutating 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?
A single front-loaded sentence with zero filler. Nothing to trim and the core action leads.
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?
With no annotations, no output schema, and only 33% schema coverage, the definition leaves too much unspecified. It doesn't cover the 'active' parameter's effect or the new-tab lifecycle, which an agent needs to invoke it confidently.
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 33%; the 'browser' param is documented in the schema, but 'url' and 'active' are not. The description partially compensates by enumerating valid URL schemes (HTTP, HTTPS, file, about:blank), but adds no meaning for 'active'.
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 ('Open') and resource ('tab') plus the accepted URL schemes, which is clear. However, it never distinguishes itself from the close sibling browser_navigate, so an agent can't tell from the text alone which one to reach for.
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 when-to-use guidance and no mention of alternatives. With browser_navigate, browser_activate_tab, and browser_close_tab in the sibling set, the description should say when a new tab (vs. navigating the current one) is appropriate, but it does not.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.