AI agents call delete_block to permanently remove resources in SiYuan MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
This tool deletes blocks (atomic units of content) from a notebook, which is an irreversible operation that destroys data. While the blast radius is primarily limited to the specific notebook being operated on (not system-wide), the permanent loss of user data makes this a Destructive rather than Write operation.
From the tool's definition Tool name 'delete_block' combined with description '删除块' (which translates to 'delete block') indicates irreversible deletion of data blocks within the SiYuan note-taking system.
Documented attack patterns abuse exactly the kind of access delete_block gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and SiYuan MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for delete_block:
{
"version": "1",
"default": "deny",
"hide": [
"delete_block"
]
}delete_block disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.
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删除块. It is categorised as a Destructive tool in the SiYuan MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the SiYuan MCP Server MCP server in PolicyLayer and add a rule for delete_block: 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 SiYuan MCP Server. Nothing to install.
delete_block is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the delete_block 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 delete_block. 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.
delete_block is provided by the SiYuan MCP Server MCP server (xgq18237/siyuan_mcp_server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 52 SiYuan MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
52 SiYuan MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.