Check if a base file exists.
AI agents call check_base_exists to retrieve information from Graph Rag Obsidian without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a simple existence check operation with no side effects. It retrieves status information about a file without altering any data, creating new resources, or triggering external operations. This is a typical read operation with minimal blast radius if misused—worst case it provides information about file locations in the user's vault.
From the tool's definition Tool name 'check_base_exists' and description 'Check if a base file exists' indicate a query operation that checks for file existence without modifying, creating, or deleting anything.
Attacks that exploit this kind of access
Check if a base file exists. It is categorised as a Read tool in the Graph Rag Obsidian MCP Server, which means it retrieves data without modifying state.
Register the Graph Rag Obsidian MCP server in PolicyLayer and add a rule for check_base_exists: 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 Graph Rag Obsidian. Nothing to install.
check_base_exists 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 check_base_exists 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 check_base_exists. 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.
check_base_exists is provided by the Graph Rag Obsidian MCP server (nickshffer/graph-rag-mcp-server). 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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