Atomically create or overwrite a note. Requires write_enabled=true. Use expected_hash for safe overwrites (read the note first, pass its hash). Omit expected_hash only when creating a new note.
AI agents use write_note to create or update resources in Vault Memory — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Vault Memory environment.
This tool creates or modifies notes in an Obsidian vault. While it can overwrite existing data, the operation is reversible—notes can be rewritten or recovered from history. It does not irreversibly delete data (which would be Destructive), nor does it execute arbitrary code.
From the tool's definition Tool description explicitly states it can 'create or overwrite a note' and requires 'write_enabled=true', indicating it modifies data reversibly.
Attacks that exploit this kind of access
Atomically create or overwrite a note. Requires write_enabled=true. Use expected_hash for safe overwrites (read the note first, pass its hash). Omit expected_hash only when creating a new note. It is categorised as a Write tool in the Vault Memory MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Vault Memory MCP server in PolicyLayer and add a rule for write_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 Vault Memory. Nothing to install.
write_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 write_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 write_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.
write_note is provided by the Vault Memory MCP server (owrede/vault-memory). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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