Closes an active browser session using its session ID, terminating the automation process and freeing resources.
Close the browser
This tool declares no required parameters. Add optional parameters from the input schema as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {},
"name": "browser_close"
}
}| Name | Required | Description | Default |
|---|---|---|---|
| sessionId | No | Session ID to close |
Changes observed during successful MCP inspections.
v0.1.3Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must carry full behavioral disclosure. It merely says 'Close the browser' and omits important details such as side effects (e.g., losing session state, irreversibility, or whether the close targets a specific session).
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 one concise sentence, front-loaded with the action. While it is under-specified, it contains no wasted words and conveys the core purpose efficiently.
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?
Given the tool's simplicity and the schema's documentation of the one parameter, the description is nearly sufficient. However, it does not explain whether the chosen sessionId affects the close behavior or mention any side effects, leaving gaps that annotations or a fuller description could fill.
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?
The schema fully describes the single sessionId parameter (100% coverage), so the baseline for parameter semantics is 3. The description adds no parameter-specific meaning beyond the schema.
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 'Close the browser' uses a specific verb and resource, clearly distinguishing it from other browser_* sibling tools. However, it is essentially a restatement of the tool name and adds no extra detail about scope or session targeting.
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 provides no context for when to use this tool, no alternatives, and no exclusions. It simply states the action without guiding the agent on when or why to invoke it.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.