AI agents call format_credit_card to retrieve information from TinyFn without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
number | string | Yes | Credit card number |
Parameters from the server's own tool schema.
Formatting a credit card number (adding spaces for readability, e.g., 1234 5678 9012 3456) is a pure data transformation with no destructive, write, execute, or financial implications. It does not move money, execute code, modify state, or delete data. While credit card data is sensitive, the tool itself merely reformats existing numbers without creating obligations or executing transactions.
From the tool's definition Tool name is 'format_credit_card' and description states it 'Format a credit card number with spaces.' This is a formatting/transformation operation that takes input and returns formatted output with no side effects, no data creation, modification, deletion,…
Attacks that exploit this kind of access
Format a credit card number with spaces. It is categorised as a Read tool in the TinyFn MCP Server, which means it retrieves data without modifying state.
format_credit_card accepts 1 parameter: number. Required: number. 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_credit_card: 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_credit_card 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_credit_card 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_credit_card. 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_credit_card 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.
format_credit_card is one line of TinyFn's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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