memory_bank_update · Memory Bank MCP: Risk & Policy

WHAT IT DOES

What memory_bank_update does on Memory Bank

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

WHY IT NEEDS A POLICY

Why memory_bank_update needs a policy

The tool modifies existing data (memory bank files) in a reversible manner. This is a Write operation—it changes content but does not permanently delete or destroy data. Severity is medium because updating project memory could have moderate impact on downstream operations if corrupted or misused, but the change is not destructive and can typically be reverted.

From the tool's definition Tool name 'memory_bank_update' and description 'Update an existing memory bank file for a specific project' explicitly indicate modification of data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

memory_bank_update Rate-limited

memory_bank_update 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": {
    "memory_bank_update": {
      "limits": [
        {
          "counter": "memory_bank_update_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about memory_bank_update

What does the memory_bank_update tool do? +

Update an existing memory bank file for a specific project. It is categorised as a Write tool in the Memory Bank MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on memory_bank_update? +

Register the Memory Bank MCP server in PolicyLayer and add a rule for memory_bank_update: 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 Memory Bank. Nothing to install.

What risk level is memory_bank_update? +

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

Can I rate-limit memory_bank_update? +

Yes. Add a rate_limit block to the memory_bank_update 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 memory_bank_update completely? +

Set action: deny in the PolicyLayer policy for memory_bank_update. 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 memory_bank_update? +

memory_bank_update is provided by the Memory Bank MCP server (@allpepper/memory-bank-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.