AI agents call link_graph to retrieve information from Obsidian MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and retrieves graph structure information from the Obsidian vault without making any changes. It is a read-only operation that returns data about note relationships. No data is modified, created, deleted, or executed. The blast radius of misuse is minimal—an agent could potentially analyze vault structure, but cannot alter it.
From the tool's definition Tool name 'link_graph' and description 'Get graph data of note connections' indicates retrieval of existing graph/connection data with no modification, creation, or deletion of notes or connections.
Documented attack patterns abuse exactly the kind of access link_graph 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 link_graph:
{
"version": "1",
"default": "deny",
"tools": {
"link_graph": {}
}
}link_graph is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get graph data of note connections. It is categorised as a Read tool in the Obsidian MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Obsidian MCP Server MCP server in PolicyLayer and add a rule for link_graph: 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.
link_graph is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the link_graph 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 link_graph. 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.
link_graph 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.
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120 Obsidian MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.