Close a User Data Stream by invalidating the listen key. Use this when you
AI agents use binance_us_close_listen_key to create or update resources in BNB Chain MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your BNB Chain MCP environment.
This tool modifies state by invalidating (closing) an active listen key used for user data streams. While the action is reversible (a new listen key can be requested), it disrupts an existing service connection and affects the user's real-time data access. This is a Write operation rather than Destructive because the listen key itself is not permanently deleted from Binance systems, just invalidated/closed.
From the tool's definition Tool name 'binance_us_close_listen_key' and description 'Close a User Data Stream by invalidating the listen key' indicate modification/revocation of an active stream resource.
Documented attack patterns abuse exactly the kind of access binance_us_close_listen_key gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and BNB Chain MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for binance_us_close_listen_key:
{
"version": "1",
"default": "deny",
"tools": {
"binance_us_close_listen_key": {
"limits": [
{
"counter": "binance_us_close_listen_key_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}binance_us_close_listen_key stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Close a User Data Stream by invalidating the listen key. Use this when you. It is categorised as a Write tool in the BNB Chain MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the BNB Chain MCP server in PolicyLayer and add a rule for binance_us_close_listen_key: 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 BNB Chain MCP. Nothing to install.
binance_us_close_listen_key is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the binance_us_close_listen_key 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 binance_us_close_listen_key. 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.
binance_us_close_listen_key is provided by the BNB Chain MCP server (nirholas/bnbchain-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 1240 BNB Chain MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
1240 BNB Chain MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.