Get the token balance of a fee sponsor account.
AI agents call get_sponsor_balance to retrieve information from Tempo without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only retrieval of balance data. While it operates in a financial system, it does not move money, commit financial obligations, execute code, or modify data. The action is a simple information retrieval that returns current state without side effects.
From the tool's definition Tool name 'get_sponsor_balance' and description 'Get the token balance of a fee sponsor account' indicate a query operation that retrieves account balance information without modifying state.
Documented attack patterns abuse exactly the kind of access get_sponsor_balance gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Tempo, and nothing reaches the server without passing your rules. This is the rule we recommend for get_sponsor_balance:
{
"version": "1",
"default": "deny",
"tools": {
"get_sponsor_balance": {}
}
}get_sponsor_balance is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get the token balance of a fee sponsor account. It is categorised as a Read tool in the Tempo MCP Server, which means it retrieves data without modifying state.
Register the Tempo MCP server in PolicyLayer and add a rule for get_sponsor_balance: 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 Tempo. Nothing to install.
get_sponsor_balance 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_sponsor_balance 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_sponsor_balance. 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_sponsor_balance is provided by the Tempo MCP server (arome3/tempo-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Tempo, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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61 Tempo tools catalogued and risk-classified — across an index of 43,000+ MCP servers.