AI agents use memento_store to create or update resources in Memento Vault — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Memento Vault environment.
The tool name 'store' strongly implies writing/persisting data to the vault. The server description mentions 'storing notes' and 'persistent knowledge capture', aligning with a Write classification. Confidence is reduced due to the empty tool description, which prevents confirming exact behavior. No evidence of destructive, financial, or execution capabilities.
From the tool's definition Tool name 'memento_store' on a server described as enabling 'storing notes, capturing sessions' — the 'store' verb implies creating or writing data persistently.
Documented attack patterns abuse exactly the kind of access memento_store gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Memento Vault, and nothing reaches the server without passing your rules. This is the rule we recommend for memento_store:
{
"version": "1",
"default": "deny",
"tools": {
"memento_store": {
"limits": [
{
"counter": "memento_store_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}memento_store 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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memento_store. It is categorised as a Write tool in the Memento Vault MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Memento Vault MCP server in PolicyLayer and add a rule for memento_store: 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 Memento Vault. Nothing to install.
memento_store 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 memento_store 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 memento_store. 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.
memento_store is provided by the Memento Vault MCP server (sandsower/memento-vault). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Memento Vault, 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.
14 Memento Vault tools catalogued and risk-classified — across an index of 43,000+ MCP servers.