AI agents use update_block to create or update resources in SiYuan MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your SiYuan MCP Server environment.
This tool modifies existing blocks within a note document system reversibly. Updates can be undone or corrected, and do not permanently destroy data (unlike delete_block). However, in a notebook/documentation system, unintended block updates could corrupt or alter important information, potentially affecting multiple dependent notes if SiYuan supports cross-references.
From the tool's definition Tool name is 'update_block' and description '更新块' (meaning 'update block' in Chinese). The name and description both indicate modification of existing data.
Documented attack patterns abuse exactly the kind of access update_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 update_block:
{
"version": "1",
"default": "deny",
"tools": {
"update_block": {
"limits": [
{
"counter": "update_block_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update_block 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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更新块. It is categorised as a Write tool in the SiYuan MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the SiYuan MCP Server MCP server in PolicyLayer and add a rule for update_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.
update_block 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_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 update_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.
update_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.