Append a paragraph to an existing note (ensures a blank-line separator).
AI agents use append_note to create or update resources in brainMD — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your brainMD environment.
This tool modifies an existing note by appending content to it. It is a reversible write operation — the note is not deleted, but its content is changed. Misuse could corrupt or pollute important notes with unwanted content, hence medium severity.
From the tool's definition Append a paragraph to an existing note (ensures a blank-line separator)
Documented attack patterns abuse exactly the kind of access append_note gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and brainMD, and nothing reaches the server without passing your rules. This is the rule we recommend for append_note:
{
"version": "1",
"default": "deny",
"tools": {
"append_note": {
"limits": [
{
"counter": "append_note_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}append_note 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.
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Append a paragraph to an existing note (ensures a blank-line separator). It is categorised as a Write tool in the brainMD MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the brainMD MCP server in PolicyLayer and add a rule for append_note: 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 brainMD. Nothing to install.
append_note 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 append_note 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 append_note. 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.
append_note is provided by the brainMD MCP server (mi4uu/brain.md). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from brainMD, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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17 brainMD tools catalogued and risk-classified — across an index of 43,000+ MCP servers.