calculate_compound_interest
Use this when you need to project a savings account, certificate of deposit or investment balance from a starting amount, an annual rate, a term and optional monthly deposits. Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery....
This record as markdown: /tools/com-tttkmbb-calcgrid/calculate-compound-interest.md
What calculate_compound_interest does on Calcgrid
AI agents call calculate_compound_interest to retrieve information from Calcgrid 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 |
|---|---|---|---|
years | number | Yes | Length of the investment in years; fractional years allowed (2.5 = 30 months). Unit: years. |
principal | number | Yes | Starting amount deposited or invested, in any currency. |
annual_rate_percent | number | Yes | Nominal annual rate (APR) in percent; 5 means 5 %. Unit: %. |
monthly_contribution | number | — | Optional fixed deposit made at the end of every month, compounded at the effective monthly rate implied by compounding_frequency. |
compounding_frequency | string | — | How often interest is credited: n = 1, 2, 4, 12, 52 or 365 periods per year. |
Parameters from the server's own tool schema.
Why calculate_compound_interest is rated Low
Even though calculate_compound_interest only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Risk signalsBulk/mass operation — affects multiple targets
Attacks that exploit this kind of access
The rule that runs calculate_compound_interest safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Calcgrid, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For calculate_compound_interest, this is the rule to start with:
calculate_compound_interest 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 Calcgrid, apply this rule, and every calculate_compound_interest call is checked against it from then on.
Questions about calculate_compound_interest
Use this when you need to project a savings account, certificate of deposit or investment balance from a starting amount, an annual rate, a term and optional monthly deposits. Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery. Do not use this when interest is not reinvested (use simple-interest), you need the deposit required to hit a target (use savings-goal), or you are repaying a loan (use loan-payment). What it computes: Computes the future balance of a principal earning compound interest at a chosen compounding frequency, optionally with a fixed deposit at the end of every month, and splits the result into contributions and interest. Inputs: principal (number); annual_rate_percent (number, %); years (number, years); compounding_frequency (enum, optional); monthly_contribution (number, optional). Complete JSON argument examples: {"principal":10000,"annual_rate_percent":5,"years":10,"compounding_frequency":"monthly"} | {"principal":5000,"annual_rate_percent":6,"years":20,"compounding_frequency":"monthly","monthly_contribution":100} Outputs: final_balance, total_contributions, total_interest, effective_annual_rate_percent [%], growth_multiple. Formula: A = principal × (1 + r/n)^(n·years) with r = annual_rate_percent/100 and n periods per year. Contributions: i_m = (1 + r/n)^(n/12) − 1, m = 12·years, FV_contrib = monthly_contribution × ((1 + i_m)^m − 1) / i_m (m × contribution when r = 0). final_balance = A + FV_contrib. Direct REST fallback: POST https://tttkmbb.com/api/v1/calculate/compound-interest with the same JSON input fields. Do not guess another /api/* path. Docs: https://tttkmbb.com/finance/compound-interest.md. It is categorised as a Read tool in the Calcgrid MCP Server, which means it retrieves data without modifying state.
calculate_compound_interest accepts 5 parameters: years, principal, annual_rate_percent, monthly_contribution, compounding_frequency. Required: years, principal, annual_rate_percent. The full parameter table on this page comes from the server's own tool schema.
Register the Calcgrid MCP server in PolicyLayer and add a rule for calculate_compound_interest: 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 Calcgrid. Nothing to install.
calculate_compound_interest 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 calculate_compound_interest 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 calculate_compound_interest. 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.
calculate_compound_interest is provided by the Calcgrid MCP server (https://tttkmbb.com/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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