extend_signal_lease · Agent Memory Bridge MCP: Risk & Policy

WHAT IT DOES

What extend_signal_lease does on Agent Memory Bridge

AI agents use extend_signal_lease to create or update resources in Agent Memory Bridge — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Agent Memory Bridge environment.

WHY IT NEEDS A POLICY

Why extend_signal_lease needs a policy

The tool appears to modify metadata of existing memory signals (extending their lease/lifetime) rather than creating new data or deleting it. This is a reversible write operation. Without a description, confidence is reduced. Severity is medium due to potential impact on memory availability for agent decision-making if leases are improperly extended, but no direct destructive or financial impact.

From the tool's definition Tool name 'extend_signal_lease' suggests modifying the lease duration/expiration of a stored signal, a state-changing operation. The verb 'extend' indicates modification of existing data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

extend_signal_lease Rate-limited

extend_signal_lease 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "extend_signal_lease": {
      "limits": [
        {
          "counter": "extend_signal_lease_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Agent Memory Bridge, so you can run agents against it safely.

FAQ

Questions about extend_signal_lease

What does the extend_signal_lease tool do? +

extend_signal_lease. It is categorised as a Write tool in the Agent Memory Bridge MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on extend_signal_lease? +

Register the Agent Memory Bridge MCP server in PolicyLayer and add a rule for extend_signal_lease: 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 Agent Memory Bridge. Nothing to install.

What risk level is extend_signal_lease? +

extend_signal_lease is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit extend_signal_lease? +

Yes. Add a rate_limit block to the extend_signal_lease 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.

How do I block extend_signal_lease completely? +

Set action: deny in the PolicyLayer policy for extend_signal_lease. 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.

What MCP server provides extend_signal_lease? +

extend_signal_lease is provided by the Agent Memory Bridge MCP server (zzhang82/agent-memory-bridge). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.