AI agents call memento_list to retrieve information from Memento Vault without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Based on naming convention and context of sibling tools focused on knowledge retrieval, this tool most likely lists stored notes or vault contents without modification. This is a Read operation with minimal security risk—an agent querying the vault causes no side effects.
From the tool's definition Tool name 'memento_list' suggests retrieval/enumeration. Server description states 'retrieval for coding agents' and 'searching the vault' as core functions. Sibling tools include 'memento_search', 'memento_get', 'memento_recall' (all Read operations).
Documented attack patterns abuse exactly the kind of access memento_list 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_list:
{
"version": "1",
"default": "deny",
"tools": {
"memento_list": {}
}
}memento_list is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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memento_list. It is categorised as a Read tool in the Memento Vault MCP Server, which means it retrieves data without modifying state.
Register the Memento Vault MCP server in PolicyLayer and add a rule for memento_list: 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_list is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the memento_list 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_list. 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_list 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.
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14 Memento Vault tools catalogued and risk-classified — across an index of 43,000+ MCP servers.