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 Sperax Ecosystem Crypto & DeFI MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Sperax Ecosystem Crypto & DeFI MCP Server environment.
Closing a listen key is a write operation that modifies the state of an existing resource (the stream subscription) but does not permanently destroy data or have irreversible consequences. The user can reconnect by obtaining a new listen key. This is clearly more impactful than a Read operation but less severe than Destructive (which would be permanent data loss) or Financial (which would involve money movement).
From the tool's definition The tool "closes" a User Data Stream by "invalidating" a listen key, which modifies the state of an active stream subscription. The description indicates a reversible action (the stream can be reopened with a new listen key) rather than permanent deletion.
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 Sperax Ecosystem Crypto & DeFI MCP Server, 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 Sperax Ecosystem Crypto & DeFI MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Sperax Ecosystem Crypto & DeFI MCP Server 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 Sperax Ecosystem Crypto & DeFI MCP Server. 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 Sperax Ecosystem Crypto & DeFI MCP Server MCP server (sperax/sperax-crypto-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Sperax Ecosystem Crypto & DeFI MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
1318 Sperax Ecosystem Crypto & DeFI MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.