AI agents use convert_to_callout 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 creates or modifies note content reversibly by applying formatting transformations. It does not execute arbitrary code, delete data, or affect financial systems. The 'medium' severity reflects that while the change is recoverable (can be undone in Obsidian), an AI agent applying callouts indiscriminately could degrade note readability or alter the semantic presentation of information in unintended ways.
From the tool's definition Tool wraps text in callout block, modifying note formatting within an Obsidian vault. The description indicates it transforms existing text by adding Markdown callout syntax, which changes the structure and appearance of note content.
Documented attack patterns abuse exactly the kind of access convert_to_callout 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 convert_to_callout:
{
"version": "1",
"default": "deny",
"tools": {
"convert_to_callout": {
"limits": [
{
"counter": "convert_to_callout_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}convert_to_callout 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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Wrap text in callout block. 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 convert_to_callout: 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.
convert_to_callout 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 convert_to_callout 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 convert_to_callout. 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.
convert_to_callout 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.