memory.write
Record a belief: subject, predicate, value, in a space. Optionally supersede an earlier fact. With evidence naming a fact the gateway fetched for this call, the value must equal it (or the field at path) and the write is verified; otherwise it is refused. Returns the new fact with its id, transac...
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What memory.write does on Agent Custody
AI agents use memory.write to create or update resources in Agent Custody, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Agent Custody environment.
Why memory.write is rated Medium
An AI agent can call memory.write faster than any human can review: one bad instruction and it creates or modifies resources in Agent Custody by the hundred, each call as confident as the last.
Attacks that exploit this kind of access
The rule that runs memory.write safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Agent Custody, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For memory.write, this is the rule to start with:
memory.write 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Agent Custody, apply this rule, and every memory.write call is checked against it from then on.
Questions about memory.write
Record a belief: subject, predicate, value, in a space. Optionally supersede an earlier fact. With evidence naming a fact the gateway fetched for this call, the value must equal it (or the field at path) and the write is verified; otherwise it is refused. Returns the new fact with its id, transaction time, actor, provenance, and source receipt. It is categorised as a Write tool in the Agent Custody MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Agent Custody MCP server in PolicyLayer and add a rule for memory.write: 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 Agent Custody. Nothing to install.
memory.write 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 memory.write 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.write. 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.write is provided by the Agent Custody MCP server (ch4r10t33r/agent-custody). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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