AI agents call get-user-by-username to retrieve information from X without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and retrieves public user profile information from X (formerly Twitter) by username. It performs a read-only operation that returns data without creating, modifying, deleting, or executing any actions. The retrieval of user details is a standard lookup operation with minimal security risk, as it accesses information typically intended to be public on the platform.
From the tool's definition Tool name 'get-user-by-username' and description 'Get details for a specific X user by username' indicate data retrieval with no modification or side effects.
Attacks that exploit this kind of access
Get details for a specific X user by username. It is categorised as a Read tool in the X MCP Server, which means it retrieves data without modifying state.
Register the X MCP server in PolicyLayer and add a rule for get-user-by-username: 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. Nothing to install.
get-user-by-username 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 get-user-by-username 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 get-user-by-username. 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.
get-user-by-username is provided by the X MCP server (siddheshutd/x-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
get-user-by-username is one line of X's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
Teams ship this data inside their own products. See what a licence covers →