AI agents use update_account to create or update resources in Paper MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Paper MCP Server environment.
Updating account details on a trading platform is a Write operation (modifies existing data reversibly). Severity is high because incorrect or malicious account modifications on a financial trading platform could affect trading permissions, account settings, or security parameters, potentially enabling unauthorized trading activity or account compromise.
From the tool's definition 'Update account details' - modifies account information on a trading platform
Documented attack patterns abuse exactly the kind of access update_account gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Paper MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for update_account:
{
"version": "1",
"default": "deny",
"tools": {
"update_account": {
"limits": [
{
"counter": "update_account_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update_account 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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Update account details. It is categorised as a Write tool in the Paper MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Paper MCP Server MCP server in PolicyLayer and add a rule for update_account: 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 Paper MCP Server. Nothing to install.
update_account 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 update_account 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 update_account. 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.
update_account is provided by the Paper MCP Server MCP server (paperinvest/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Paper MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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23 Paper MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.