AI agents call memory_check_contradiction to retrieve information from Mementos without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
memory_check_contradiction is a validation/querying tool that reads existing memory facts to perform conflict detection. It has no side effects—it does not create, modify, delete, or execute external operations. The output informs decision-making but does not alter state. While it is part of a memory system alongside write/delete tools (entity_create, entity_delete, bulk_forget), this specific tool is read-only.
From the tool's definition Tool performs a check/query operation ('Check if a new memory would contradict existing high-importance facts') that returns information ('Returns contradiction details if found') without modifying or deleting any data.
Attacks that exploit this kind of access
Check if a new memory would contradict existing high-importance facts. Call before saving to detect conflicts. Returns contradiction details if found. It is categorised as a Read tool in the Mementos MCP Server, which means it retrieves data without modifying state.
Register the Mementos MCP server in PolicyLayer and add a rule for memory_check_contradiction: 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 Mementos. Nothing to install.
memory_check_contradiction 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 memory_check_contradiction 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 memory_check_contradiction. 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.
memory_check_contradiction is provided by the Mementos MCP server (@hasna/mementos). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
memory_check_contradiction is one line of Mementos's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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