Append an event to a session timeline. Agents call this during a session to record decisions, experiments, rejections, and results in real-time. Subscribers to the replay resource receive real-time notifications.
AI agents use session_append_event to create or update resources in Engram — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Engram environment.
This tool writes new event data to a session timeline. It creates/appends records but does not delete or overwrite existing data, making it a Write operation. Severity is medium because an AI agent could pollute or corrupt session history with false or misleading events, affecting downstream reasoning and memory retrieval across projects.
From the tool's definition Append an event to a session timeline... record decisions, experiments, rejections, and results in real-time
Attacks that exploit this kind of access
Append an event to a session timeline. Agents call this during a session to record decisions, experiments, rejections, and results in real-time. Subscribers to the replay resource receive real-time notifications. It is categorised as a Write tool in the Engram MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Engram MCP server in PolicyLayer and add a rule for session_append_event: 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 Engram. Nothing to install.
session_append_event 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 session_append_event 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 session_append_event. 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.
session_append_event is provided by the Engram MCP server (tinydarkforge/engram). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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