Stores or updates a custom key-value entry organized by category. Use for any structured data not covered by decisions, progress, or patterns (e.g., glossary terms under category
AI agents use log_custom_data to create or update resources in Engrams — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Engrams environment.
The tool creates or modifies structured data (key-value entries) in persistent memory. This is a reversible write operation with low blast radius — it stores metadata/context entries that can be overwritten or deleted, and does not execute code, delete data destructively, or involve financial transactions.
From the tool's definition 'Stores or updates a custom key-value entry organized by category'
Documented attack patterns abuse exactly the kind of access log_custom_data gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Engrams, and nothing reaches the server without passing your rules. This is the rule we recommend for log_custom_data:
{
"version": "1",
"default": "deny",
"tools": {
"log_custom_data": {
"limits": [
{
"counter": "log_custom_data_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}log_custom_data 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.
Free to start. No card required.
Stores or updates a custom key-value entry organized by category. Use for any structured data not covered by decisions, progress, or patterns (e.g., glossary terms under category. It is categorised as a Write tool in the Engrams MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Engrams MCP server in PolicyLayer and add a rule for log_custom_data: 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 Engrams. Nothing to install.
log_custom_data 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 log_custom_data 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 log_custom_data. 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.
log_custom_data is provided by the Engrams MCP server (stevebrownlee/engrams). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Engrams, 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.
42 Engrams tools catalogued and risk-classified — across an index of 43,000+ MCP servers.