AI agents use write_memory_bank_file to create or update resources in Memory Bank MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Memory Bank MCP environment.
This tool modifies data reversibly by writing to files in a Memory Bank. It does not delete data (which would be Destructive), execute arbitrary code (Execute), or move money (Financial). The severity is medium because misuse could corrupt important context or decision logs maintained across sessions, but the impact is typically recoverable through backups or manual correction.
From the tool's definition Tool name is 'write_memory_bank_file' and description states 'Write to a Memory Bank file', indicating it creates or modifies data within a structured repository.
Documented attack patterns abuse exactly the kind of access write_memory_bank_file gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Memory Bank MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for write_memory_bank_file:
{
"version": "1",
"default": "deny",
"tools": {
"write_memory_bank_file": {
"limits": [
{
"counter": "write_memory_bank_file_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}write_memory_bank_file 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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Write to a Memory Bank file. It is categorised as a Write tool in the Memory Bank MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Memory Bank MCP server in PolicyLayer and add a rule for write_memory_bank_file: 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 MCP. Nothing to install.
write_memory_bank_file 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 write_memory_bank_file 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 write_memory_bank_file. 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.
write_memory_bank_file is provided by the Memory Bank MCP server (movibe/memory-bank-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Memory Bank MCP, 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.
15 Memory Bank MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.