Acknowledge entries that were processed by a consumer group. Args: key (str): The stream key. group_name (str): The consumer group name. entry_ids (List[str]): Entry IDs to acknowledge. Returns: str: Confirmation message or an error message.
AI agents use xack to create or update resources in Redis MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Redis MCP Server environment.
XACK marks stream entries as acknowledged in a consumer group's pending entries list, which is a reversible state modification (entries remain in the stream, only the pending/unacknowledged state changes). This is a Write operation — it modifies Redis stream consumer group state but does not delete data or execute code.
From the tool's definition Acknowledge entries that were processed by a consumer group
Documented attack patterns abuse exactly the kind of access xack gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Redis MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for xack:
{
"version": "1",
"default": "deny",
"tools": {
"xack": {
"limits": [
{
"counter": "xack_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}xack 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.
Free to start. No card required.
Acknowledge entries that were processed by a consumer group. Args: key (str): The stream key. group_name (str): The consumer group name. entry_ids (List[str]): Entry IDs to acknowledge. Returns: str: Confirmation message or an error message. It is categorised as a Write tool in the Redis MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Redis MCP Server MCP server in PolicyLayer and add a rule for xack: 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 Redis MCP Server. Nothing to install.
xack 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 xack 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 xack. 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.
xack is provided by the Redis MCP Server MCP server (redis/mcp-redis). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 53 Redis MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
53 Redis MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.