oauth_v2_exchange · Slack MCP: Risk & Policy

WHAT IT DOES

What oauth_v2_exchange does on Slack

AI agents use oauth_v2_exchange to create or update resources in Slack — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Slack environment.

WHY IT NEEDS A POLICY

Why oauth_v2_exchange needs a policy

This tool modifies authentication state by issuing new access tokens in exchange for legacy ones. While not directly destructive or financial, token exchange is a Write operation because it creates new credentials and alters the authentication landscape.

From the tool's definition Tool exchanges and transforms access tokens, which modifies authentication credentials. The description states 'Exchange a legacy access token for a new expiring access token,' indicating it creates or replaces security-sensitive tokens.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

oauth_v2_exchange Rate-limited

oauth_v2_exchange stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "oauth_v2_exchange": {
      "limits": [
        {
          "counter": "oauth_v2_exchange_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Slack, so you can run agents against it safely.

FAQ

Questions about oauth_v2_exchange

What does the oauth_v2_exchange tool do? +

Exchange a legacy access token for a new expiring access token. It is categorised as a Write tool in the Slack MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on oauth_v2_exchange? +

Register the Slack MCP server in PolicyLayer and add a rule for oauth_v2_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 Slack. Nothing to install.

What risk level is oauth_v2_exchange? +

oauth_v2_exchange is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit oauth_v2_exchange? +

Yes. Add a rate_limit block to the oauth_v2_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.

How do I block oauth_v2_exchange completely? +

Set action: deny in the PolicyLayer policy for oauth_v2_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.

What MCP server provides oauth_v2_exchange? +

oauth_v2_exchange is provided by the Slack MCP server (karbassi/slack-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.