MCP Tool: Updates the YAML frontmatter of an existing note, with backup option.
AI agents use update_note_metadata to create or update resources in Obsidian MCP Tool Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Obsidian MCP Tool Server environment.
This tool creates or modifies data (note metadata/frontmatter) reversibly. It does not delete, execute code, trigger external operations, or move money. The blast radius is medium because corrupted frontmatter could break note properties or links in Obsidian, but changes are recoverable via the backup feature and can be manually edited.
From the tool's definition Tool description states it 'Updates the YAML frontmatter of an existing note', which modifies metadata in a reversible manner. The 'backup option' indicates modifications can be undone.
Documented attack patterns abuse exactly the kind of access update_note_metadata gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Obsidian MCP Tool Server, and nothing reaches the server without passing your rules. This is the rule we recommend for update_note_metadata:
{
"version": "1",
"default": "deny",
"tools": {
"update_note_metadata": {
"limits": [
{
"counter": "update_note_metadata_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update_note_metadata 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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MCP Tool: Updates the YAML frontmatter of an existing note, with backup option. It is categorised as a Write tool in the Obsidian MCP Tool Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Obsidian MCP Tool Server MCP server in PolicyLayer and add a rule for update_note_metadata: 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 Tool Server. Nothing to install.
update_note_metadata 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_metadata 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_metadata. 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_metadata is provided by the Obsidian MCP Tool Server MCP server (rwb3n/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 18 Obsidian MCP Tool Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
18 Obsidian MCP Tool Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.