Append simplified blocks or Markdown to a page. Inserts at the end by default; pass after_block_id to insert immediately after a specific direct child block.
AI agents use append_blocks to create or update resources in Notion Private Api — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Notion Private Api environment.
This tool creates new content by appending blocks to a Notion page. It is a reversible write operation (blocks can be deleted afterward), with no indication of irreversible deletion or financial action. Severity is medium because an agent could insert unwanted or malicious content into any page in the entire workspace given the private API access described.
From the tool's definition 'Append simplified blocks or Markdown to a page. Inserts at the end by default; pass after_block_id to insert immediately after a specific direct child block.'
Attacks that exploit this kind of access
Append simplified blocks or Markdown to a page. Inserts at the end by default; pass after_block_id to insert immediately after a specific direct child block. It is categorised as a Write tool in the Notion Private Api MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Notion Private Api MCP server in PolicyLayer and add a rule for append_blocks: 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 Notion Private Api. Nothing to install.
append_blocks 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 append_blocks 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 append_blocks. 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.
append_blocks is provided by the Notion Private Api MCP server (kirvigen/notion-private-api-mcp). 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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