AI agents call list_supported_providers to retrieve information from Email MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and displays a list of supported email providers without modifying, executing operations, or causing side effects. It is a simple informational query, fitting the 'Read' category. The severity is low because disclosure of supported providers poses minimal security risk and does not enable direct account compromise or data manipulation.
From the tool's definition Tool name 'list_supported_providers' and description '列出支持的邮箱提供商' (list supported email providers) indicate a query/retrieval operation that returns information about available email service providers.
Documented attack patterns abuse exactly the kind of access list_supported_providers gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Email MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_supported_providers:
{
"version": "1",
"default": "deny",
"tools": {
"list_supported_providers": {}
}
}list_supported_providers is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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列出支持的邮箱提供商. It is categorised as a Read tool in the Email MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Email MCP Server MCP server in PolicyLayer and add a rule for list_supported_providers: 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 MCP Server. Nothing to install.
list_supported_providers 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_supported_providers 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_supported_providers. 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_supported_providers is provided by the Email MCP Server MCP server (timecyber/email-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 7 Email MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
7 Email MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.