AI agents use writeNote to create or update resources in Obsidian MCP REST Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Obsidian MCP REST Server environment.
The tool creates or modifies notes within the Obsidian vault. These operations are reversible (notes can be re-edited or deleted) and are characteristic of Write category tools. Severity is medium because misuse could result in overwriting important notes or vault content, but the impact is limited to the specific vault instance and is recoverable.
From the tool's definition Tool description explicitly states 'Create or update a note' which are reversible write operations on vault data
Documented attack patterns abuse exactly the kind of access writeNote gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Obsidian MCP REST Server, and nothing reaches the server without passing your rules. This is the rule we recommend for writeNote:
{
"version": "1",
"default": "deny",
"tools": {
"writeNote": {
"limits": [
{
"counter": "writenote_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}writeNote 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.
Create or update a note. It is categorised as a Write tool in the Obsidian MCP REST Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Obsidian MCP REST Server MCP server in PolicyLayer and add a rule for writeNote: 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 REST Server. Nothing to install.
writeNote 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 writeNote 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 writeNote. 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.
writeNote is provided by the Obsidian MCP REST Server MCP server (publikprinciple/obsidian-mcp-rest). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 5 Obsidian MCP REST Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
5 Obsidian MCP REST Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.