Cancel a running browser agent or research task. Args: task_id: Task ID (full or prefix match) Returns: JSON with success status and message
AI agents invoke task_cancel to trigger actions in Browser-Use MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
Cancelling a running task is an external operational action that terminates an in-progress process. It is not a simple read, nor does it delete stored data irreversibly. It triggers an operational side effect (stopping a task), placing it in the Execute category. Misuse could disrupt ongoing research or browser automation workflows, warranting medium severity.
From the tool's definition Cancel a running browser agent or research task
Documented attack patterns abuse exactly the kind of access task_cancel gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Browser-Use MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for task_cancel:
{
"version": "1",
"default": "deny",
"tools": {
"task_cancel": {
"limits": [
{
"counter": "task_cancel_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}task_cancel stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Cancel a running browser agent or research task. Args: task_id: Task ID (full or prefix match) Returns: JSON with success status and message. It is categorised as a Execute tool in the Browser-Use MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Browser-Use MCP Server MCP server in PolicyLayer and add a rule for task_cancel: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Browser-Use MCP Server. Nothing to install.
task_cancel is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the task_cancel rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for task_cancel. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
task_cancel is provided by the Browser-Use MCP Server MCP server (saik0s/mcp-browser-use). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 9 Browser-Use MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
9 Browser-Use MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.