Purpose: List contacts from Resend. Optionally filter by segment. Use to discover contact IDs or emails. NOT for: Listing segments (use list-segments). Not for listing sent emails (use list-emails) or broadcasts (use list-broadcasts). Returns: For each contact: id, email, first_name, last_name, u...
AI agents call list-contacts to retrieve information from Email Sending MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and queries existing contact data without side effects. It is a read-only operation that fetches contact information for discovery purposes. No data is created, modified, deleted, or executed. The blast radius if misused by an AI agent is minimal—at worst, an agent could retrieve contact information that may already be accessible through normal UI operations.
From the tool's definition Tool description explicitly states 'List contacts from Resend' and 'Use to discover contact IDs or emails.' Returns contact data (id, email, first_name, last_name, unsubscribed, created_at) with no modification, deletion, or execution capabilities.
Documented attack patterns abuse exactly the kind of access list-contacts 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 list-contacts:
{
"version": "1",
"default": "deny",
"tools": {
"list-contacts": {}
}
}list-contacts is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Purpose: List contacts from Resend. Optionally filter by segment. Use to discover contact IDs or emails. NOT for: Listing segments (use list-segments). Not for listing sent emails (use list-emails) or broadcasts (use list-broadcasts). Returns: For each contact: id, email, first_name, last_name, unsubscribed, created_at. When to use: User asks. It is categorised as a Read tool in the Email Sending MCP MCP Server, which means it retrieves data without modifying state.
Register the Email Sending MCP server in PolicyLayer and add a rule for list-contacts: 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.
list-contacts is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list-contacts 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 list-contacts. 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.
list-contacts 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.