Update the ACL policy for your tailnet. Accepts the full policy as a string to preserve formatting, comments, and trailing commas (HuJSON). You MUST pass the ETag from tailscale_get_acl to prevent overwriting concurrent changes. Always get the current ACL first, make targeted edits to the text, a...
Part of the Tailscale MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.
AI agents use tailscale_update_acl to create or modify resources in Tailscale. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call tailscale_update_acl repeatedly, creating or modifying resources faster than any human could review. Intercept's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Tailscale.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
tools:
tailscale_update_acl:
rules:
- action: allow
rate_limit:
max: 30
window: 60See the full Tailscale policy for all 89 tools.
Agents calling write-class tools like tailscale_update_acl have been implicated in these attack patterns. Read the full case and prevention policy for each:
Other tools in the Write risk category across the catalogue. The same policy patterns (rate-limit, validate) apply to each.
Update the ACL policy for your tailnet. Accepts the full policy as a string to preserve formatting, comments, and trailing commas (HuJSON). You MUST pass the ETag from tailscale_get_acl to prevent overwriting concurrent changes. Always get the current ACL first, make targeted edits to the text, and pass the full modified text back.. It is categorised as a Write tool in the Tailscale MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Add a rule in your Intercept YAML policy under the tools section for tailscale_update_acl. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the Tailscale MCP server.
tailscale_update_acl 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 tailscale_update_acl rule in your Intercept 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 Intercept policy for tailscale_update_acl. 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.
tailscale_update_acl is provided by the Tailscale MCP server (@yawlabs/tailscale-mcp). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic policy on every MCP tool call. Per-identity grants. Full audit log.