rule_of_72

Calculate time to double investment using Rule of 72.

SERVERTinyFn SOURCEhttps://api.tinyfn.io/mcp/all/

Low RISK CLASS

Category Read

Parameters 11 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-tinyfn-tinyfn/rule-of-72.md

WHAT IT DOES

What rule_of_72 does on TinyFn

AI agents call rule_of_72 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
`rate`	number	Yes	Annual interest rate (percentage)

Parameters from the server's own tool schema.

RISK

Why rule_of_72 is rated Low

This is a deterministic financial formula calculator (Rule of 72 is a quick mental math formula). It takes investment parameters as input and returns a calculated estimate of doubling time. It performs no mutations, no external operations, and does not execute actual financial transactions or create obligations. It is purely informational/computational, fitting the Read category.

From the tool's definition Tool name 'rule_of_72' and description 'Calculate time to double investment using Rule of 72' indicate a pure calculation utility that retrieves/computes a mathematical result without modifying any data, executing external operations, or committing financial…

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs rule_of_72 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 rule_of_72, this is the rule to start with:

rule_of_72 Allowed

rule_of_72 is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "rule_of_72": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect TinyFn, apply this rule, and every rule_of_72 call is checked against it from then on.

FAQ

Questions about rule_of_72

What does the rule_of_72 tool do? +

Calculate time to double investment using Rule of 72. It is categorised as a Read tool in the TinyFn MCP Server, which means it retrieves data without modifying state.

What parameters does rule_of_72 accept? +

rule_of_72 accepts 1 parameter: rate. Required: rate. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on rule_of_72? +

Register the TinyFn MCP server in PolicyLayer and add a rule for rule_of_72: 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.

What risk level is rule_of_72? +

rule_of_72 is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit rule_of_72? +

Yes. Add a rate_limit block to the rule_of_72 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.

How do I block rule_of_72 completely? +

Set action: deny in the PolicyLayer policy for rule_of_72. 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.

What MCP server provides rule_of_72? +

rule_of_72 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.

KEEP EXPLORING

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