Update template metadata by ID, alias, or Resend dashboard URL (name, subject, from, html, variables, etc.). After updating a published template, use publish-template again to make the changes live. To edit TipTap content, use compose-template instead. Note on html/text fields: Setting html or te...
AI agents use update-template to create or update resources in Email Sending MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Email Sending MCP environment.
This tool modifies template data reversibly—updated templates can be reverted or corrected, and the changes do not become permanent until explicitly published. However, severity is high because templates are typically used to send emails at scale (as evidenced by sibling tools like compose-broadcast and create-broadcast), so a malicious modification could poison email communications affecting many recipients.
From the tool's definition Tool description states it "Update[s] template metadata by ID, alias, or Resend dashboard URL (name, subject, from, html, variables, etc.)" and explicitly notes that updating published templates requires subsequent republication to "make the changes live."…
Documented attack patterns abuse exactly the kind of access update-template gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Email Sending MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for update-template:
{
"version": "1",
"default": "deny",
"tools": {
"update-template": {
"limits": [
{
"counter": "update-template_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update-template 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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Update template metadata by ID, alias, or Resend dashboard URL (name, subject, from, html, variables, etc.). After updating a published template, use publish-template again to make the changes live. To edit TipTap content, use compose-template instead. Note on html/text fields: Setting html or text via this tool replaces any content previously set via compose-template. This switch is lossy — some content or formatting may be lost. Prefer compose-template for content changes. If the template was composed with TipTap content, ask the user before overwriting it with raw HTML. It is categorised as a Write tool in the Email Sending MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Email Sending MCP server in PolicyLayer and add a rule for update-template: 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 Email Sending MCP. Nothing to install.
update-template 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-template 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-template. 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-template is provided by the Email Sending MCP server (resend/resend-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 77 Email Sending MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
77 Email Sending MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.