Exchange OAuth code for OIDC token during SSO authorization
AI agents invoke sso_token_exchange to trigger actions in Vercel MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool performs an OAuth/OIDC token exchange operation, which triggers an external authentication/authorization flow and returns credentials. It's not purely reading data — it initiates and completes an authorization handshake that results in issuing access tokens. Misuse could lead to unauthorized access token generation, hence medium severity.
From the tool's definition Exchange OAuth code for OIDC token during SSO authorization
Documented attack patterns abuse exactly the kind of access sso_token_exchange 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 sso_token_exchange:
{
"version": "1",
"default": "deny",
"tools": {
"sso_token_exchange": {
"limits": [
{
"counter": "sso_token_exchange_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}sso_token_exchange stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Exchange OAuth code for OIDC token during SSO authorization. It is categorised as a Execute tool in the Vercel MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Vercel MCP Server MCP server in PolicyLayer and add a rule for sso_token_exchange: 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.
sso_token_exchange is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the sso_token_exchange 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 sso_token_exchange. 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.
sso_token_exchange 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.
Free to start. No card required.
154 Vercel MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.