This record as markdown: /tools/io-tinyfn-tinyfn/format-currency.md
What format_currency does on TinyFn
AI agents call format_currency to retrieve information from TinyFn without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
amount | number | Yes | Amount to format |
locale | string | — | Locale for formatting |
currency | string | — | Currency code (USD, EUR, GBP, etc.) |
Parameters from the server's own tool schema.
Why format_currency is rated Low
This tool takes a currency amount as input and returns a formatted string representation. It performs no financial transactions, does not modify data, does not execute external code, and is inherently deterministic and reversible. It is purely a display/transformation utility, classified as Read with low severity since misuse would only affect output formatting with no operational consequences.
From the tool's definition Tool name 'format_currency' and description 'Format an amount as currency' indicate a formatting/display operation that retrieves or transforms data without side effects.
Attacks that exploit this kind of access
The rule that runs format_currency safely
PolicyLayer is an MCP gateway: it sits between your AI agents and TinyFn, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For format_currency, this is the rule to start with:
format_currency is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect TinyFn, apply this rule, and every format_currency call is checked against it from then on.
Questions about format_currency
Format an amount as currency. It is categorised as a Read tool in the TinyFn MCP Server, which means it retrieves data without modifying state.
format_currency accepts 3 parameters: amount, locale, currency. Required: amount. The full parameter table on this page comes from the server's own tool schema.
Register the TinyFn MCP server in PolicyLayer and add a rule for format_currency: 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 TinyFn. Nothing to install.
format_currency 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 format_currency 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 format_currency. 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.
format_currency is provided by the TinyFn MCP server (https://api.tinyfn.io/mcp/all/). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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