Create a new API key in Resend. The token is only shown once upon creation, so you MUST display it to the user.
AI agents use create-api-key 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 is a Write operation as it creates a new persistent resource (API key) in the email service platform. It is not Destructive because API keys can be revoked or replaced. Severity is high because a compromised API key could allow unauthorized access to the Resend account and email capabilities, though it does not directly move money or execute arbitrary code.
From the tool's definition Tool creates a new API key resource in Resend. Description states 'Create a new API key in Resend' and emphasizes the token is displayed only once, indicating irreversible creation of a credential.
Documented attack patterns abuse exactly the kind of access create-api-key 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 create-api-key:
{
"version": "1",
"default": "deny",
"tools": {
"create-api-key": {
"limits": [
{
"counter": "create-api-key_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create-api-key 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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Create a new API key in Resend. The token is only shown once upon creation, so you MUST display it to the user. 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 create-api-key: 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.
create-api-key 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 create-api-key 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 create-api-key. 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.
create-api-key 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.
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77 Email Sending MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.