Purpose: List all segments in the account. Use to get segment IDs required by create-contact, create-broadcast, list-contacts. NOT for: Listing contacts inside a segment (use list-contacts with segmentId). Not for listing broadcasts (use list-broadcasts). Returns: For each segment: name, id, crea...
AI agents call list-segments 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 segment information without side effects. It is a simple read operation that queries existing data to help users obtain segment IDs for use with other tools. The low severity reflects minimal blast radius if misused—an agent could only enumerate segment metadata, which poses no direct harm.
From the tool's definition Tool description explicitly states 'List all segments in the account' and returns metadata (name, id, created_at) with pagination support. No modification, deletion, or external action is performed.
Documented attack patterns abuse exactly the kind of access list-segments 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-segments:
{
"version": "1",
"default": "deny",
"tools": {
"list-segments": {}
}
}list-segments 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 all segments in the account. Use to get segment IDs required by create-contact, create-broadcast, list-contacts. NOT for: Listing contacts inside a segment (use list-contacts with segmentId). Not for listing broadcasts (use list-broadcasts). Returns: For each segment: name, id, created_at. Use pagination (limit, after/before) for large lists. When to use: User says. 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-segments: 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-segments 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-segments 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-segments. 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-segments 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.