Amaltash Investment & Retirement Calculators

Compound Interest Calculator

compound_interest

Read-onlyIdempotent

Compound interest calculator with an interactive chart. Works out what a starting amount and monthly deposits grow to at a fixed rate, compounded daily, monthly or yearly, and gives the APY. Use it for savings growth, CD and high-yield savings balances, future value at a fixed rate, and questions like what $10,000 becomes in 10 years at 5%.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "principal": "<principal>",
      "per_month": "<per_month>",
      "annual_rate_percent": "<annual_rate_percent>",
      "compounding": "<compounding>",
      "years": "<years>"
    },
    "name": "compound_interest"
  }
}

Input Schema

Name	Required	Description
`years`	Yes	Whole years, from 1 to 60.
`per_month`	Yes	Dollars added at the end of each month.
`principal`	Yes	Starting amount, in US dollars.
`compounding`	Yes	How often interest is added to the balance.
`annual_rate_percent`	Yes	Yearly interest rate as a percent, so 5 means 5%.

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 10, 2026

TDQS

A3.9/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover the safety profile (readOnly, idempotent, closed-world, non-destructive), so the description is free to add substance and does: it discloses the fixed-rate assumption, an interactive chart as an output, and an APY figure. The main omission is the exact compounding/deposit mechanics narrative, though the schema states deposits land at month end.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with what the tool computes, followed by use cases and one illustrative example. Every clause contributes; the phrasing is slightly padded ('Works out what a starting amount and monthly deposits grow to') but not wasteful.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description partially compensates by mentioning the interactive chart and the APY result. It does not enumerate the full return shape (final balance vs. contributions vs. interest earned), which an agent might want to know. For a five-parameter calculator with full schema coverage, that gap is minor.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all five parameters (including the compounding enum) are already documented with ranges and units. The description restates the compounding options and the deposit concept without adding format or precision beyond the schema. Baseline 3 is appropriate when the schema does the heavy lifting.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific resource and computation: growth of a starting amount plus monthly deposits at a fixed rate, with selectable compounding and an APY figure. It also gives a concrete example question ('what $10,000 becomes in 10 years at 5%'), which pins the scope tightly. It never names a sibling tool (e.g. dca_vs_lump_sum or retirement_plan), so the boundary is implied by domain rather than stated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives explicit use cases: savings growth, CD and high-yield savings balances, future value at a fixed rate. That is clear when-to-use guidance with examples. There are no exclusions or named alternatives, so an agent must infer on its own that retirement planning or drawdown questions belong elsewhere.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

All Amaltash Investment & Retirement Calculators tools Inspect

Try in Browser

One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources

Need Help?