AI agents use followUser to create or update resources in Twitter Client MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Twitter Client MCP environment.
Following a user is a reversible social action (can be undone by unfollowing), so it falls under Write rather than Destructive. However, misuse could lead to unwanted follows or social manipulation, giving it medium severity.
From the tool's definition 'Follow a Twitter user' — creates a new follow relationship between the authenticated account and a target user.
Documented attack patterns abuse exactly the kind of access followUser gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Twitter Client MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for followUser:
{
"version": "1",
"default": "deny",
"tools": {
"followUser": {
"limits": [
{
"counter": "followuser_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}followUser 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.
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Follow a Twitter user. It is categorised as a Write tool in the Twitter Client MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Twitter Client MCP server in PolicyLayer and add a rule for followUser: 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 Twitter Client MCP. Nothing to install.
followUser is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the followUser 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 followUser. 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.
followUser is provided by the Twitter Client MCP server (mzkrasner/twitter-client-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Twitter Client MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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20 Twitter Client MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.