AI agents use add_list_member to create or update resources in X(Twitter) V2 MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your X(Twitter) V2 MCP Server environment.
This tool modifies data (adds a member to a Twitter list) but does so reversibly. It creates a new relationship/association rather than destructively deleting or executing arbitrary operations. The lack of description lowers confidence slightly, but the name and context are clear.
From the tool's definition Tool name 'add_list_member' indicates modification of list membership on Twitter/X. Sibling tools include 'create_list' and 'get_owned_lists', establishing this as a list management API. The action is reversible (members can be removed).
Documented attack patterns abuse exactly the kind of access add_list_member gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and X(Twitter) V2 MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for add_list_member:
{
"version": "1",
"default": "deny",
"tools": {
"add_list_member": {
"limits": [
{
"counter": "add_list_member_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_list_member 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.
Free to start. No card required.
add_list_member. It is categorised as a Write tool in the X(Twitter) V2 MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the X(Twitter) V2 MCP Server MCP server in PolicyLayer and add a rule for add_list_member: 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 X(Twitter) V2 MCP Server. Nothing to install.
add_list_member 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 add_list_member 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 add_list_member. 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.
add_list_member is provided by the X(Twitter) V2 MCP Server MCP server (nexusx-mcp/x-v2-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from X(Twitter) V2 MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
16 X(Twitter) V2 MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.