AI agents call check_allowance to retrieve information from Justlend without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only reads the approval status of a TRC20 token for a jToken market on TRON. It performs no writes, executions, deletions, or financial transactions. It is a simple state query with no side effects, making it a Read category tool with low severity.
From the tool's definition Tool name 'check_allowance' and description 'Check if the underlying TRC20 token has been approved for a jToken market' indicate a query operation that retrieves approval status without modifying state.
Attacks that exploit this kind of access
Check if the underlying TRC20 token has been approved for a jToken market. It is categorised as a Read tool in the Justlend MCP Server, which means it retrieves data without modifying state.
Register the Justlend MCP server in PolicyLayer and add a rule for check_allowance: 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 Justlend. Nothing to install.
check_allowance 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 check_allowance 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 check_allowance. 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.
check_allowance is provided by the Justlend MCP server (justlend/mcp-server-justlend). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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