Append content to the end of an existing note
AI agents use append_to_note to create or update resources in Obsidian MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Obsidian MCP Server environment.
This tool modifies existing notes by appending content, which is a reversible write operation. While it changes data in the Obsidian vault, it does not delete or irreversibly overwrite information. The severity is medium because unintended appends to notes could corrupt note structure or inject unwanted content, but the effect is localized to a single note and can be undone.
From the tool's definition Tool name 'append_to_note' and description 'Append content to the end of an existing note' indicate modification of existing data. The action is reversible (content can be removed), making it Write rather than Destructive.
Documented attack patterns abuse exactly the kind of access append_to_note gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Obsidian MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for append_to_note:
{
"version": "1",
"default": "deny",
"tools": {
"append_to_note": {
"limits": [
{
"counter": "append_to_note_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}append_to_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.
Free to start. No card required.
Append content to the end of an existing note. It is categorised as a Write tool in the Obsidian MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Obsidian MCP Server MCP server in PolicyLayer and add a rule for append_to_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 Obsidian MCP Server. Nothing to install.
append_to_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_to_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_to_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_to_note is provided by the Obsidian MCP Server MCP server (kynlos/obsidian-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Obsidian MCP Server, 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.
120 Obsidian MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.