AI agents call list_auth_tokens to retrieve information from Vercel 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 authentication tokens associated with a user account. While auth tokens are sensitive and their exposure could be concerning, the tool itself only performs a read operation—it queries existing data without creating, modifying, deleting, executing code, or moving money.
From the tool's definition Tool name 'list_auth_tokens' and description 'Retrieve a list of the current User' indicate a query/retrieval operation with no modification or execution of code/commands.
Documented attack patterns abuse exactly the kind of access list_auth_tokens gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Vercel MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_auth_tokens:
{
"version": "1",
"default": "deny",
"tools": {
"list_auth_tokens": {}
}
}list_auth_tokens is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Retrieve a list of the current User. It is categorised as a Read tool in the Vercel MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Vercel MCP Server MCP server in PolicyLayer and add a rule for list_auth_tokens: 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 Vercel MCP Server. Nothing to install.
list_auth_tokens 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_auth_tokens 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_auth_tokens. 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_auth_tokens is provided by the Vercel MCP Server MCP server (quegenx/vercel-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 154 Vercel MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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154 Vercel MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.