Update content in an existing note using text replacements or precise insertions
AI agents use update_note to create or update resources in Obsidian MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Obsidian MCP environment.
This tool modifies note content but does not delete or irreversibly destroy data. Text replacements and insertions are reversible operations—previous content can be recovered or corrected. While it operates on user knowledge bases which are valuable, the impact is contained to individual note content rather than system-wide or financial effects.
From the tool's definition Tool name 'update_note' and description 'Update content in an existing note using text replacements or precise insertions' directly indicate modification of existing data through reversible operations (text replacement and insertion).
Documented attack patterns abuse exactly the kind of access update_note gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Obsidian MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for update_note:
{
"version": "1",
"default": "deny",
"tools": {
"update_note": {
"limits": [
{
"counter": "update_note_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update_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.
Update content in an existing note using text replacements or precise insertions. It is categorised as a Write tool in the Obsidian MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Obsidian MCP server in PolicyLayer and add a rule for update_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. Nothing to install.
update_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 update_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 update_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.
update_note is provided by the Obsidian MCP server (newtype-01/obsidian-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 11 Obsidian MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
11 Obsidian MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.