GadgetHumans API Hub

investment

Project an investment's future value with contributions over a number of years. Pure CPU, instant.

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": {
      "amount": "<amount>"
    },
    "name": "investment"
  }
}

Input Schema

Name	Required	Description
`rate`	No	Annual return percent
`years`	No	Years
`amount`	Yes	Initial amount

Schema Changelog

Changes observed during successful MCP inspections.

AddedNov 8, 2026
RemovedNov 6, 2026

Changed4 schema fields changedNov 3, 2026

addedInput schema / properties / amount

Added value: +{
+  "description": "Initial amount",
+  "type": "number"
+}

addedInput schema / properties / rate

Added value: +{
+  "description": "Annual return percent",
+  "type": "number"
+}

addedInput schema / properties / years

Added value: +{
+  "description": "Years",
+  "type": "number"
+}

addedInput schema / required
```
Added value: +[
+  "amount"
+]
```

AddedNov 2, 2026

TDQS

C2.4/5.0

Behavior2/5

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

With no annotations, the description carries the full burden of behavioral disclosure. 'Pure CPU, instant' gives a hint about performance and safety, but it fails to explain compounding frequency, contribution timing, or what the return value looks like. The mention of contributions without a corresponding parameter is especially confusing.

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?

The description is brief and front-loaded, with zero wasted words. 'Pure CPU, instant' efficiently communicates performance characteristics. The only issue is the inaccurate 'contributions' phrase, which slightly undermines clarity.

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

Completeness2/5

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

For a financial projection tool with no output schema and no annotations, the description is missing key details: compounding assumptions, contribution handling, and expected output format. The agent cannot reliably determine how to invoke it correctly beyond passing the three basic parameters.

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

Parameters2/5

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

Schema coverage is 100%, so the baseline would be 3, but the description introduces 'contributions' as if it were an input when no such parameter exists. This adds misleading semantics rather than helpful meaning beyond the schema. The other parameters (amount, rate, years) receive no additional explanation.

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

Purpose3/5

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

The description states a specific action: projecting an investment's future value over years. However, it mentions 'contributions' that are not represented by any input parameter, creating ambiguity about what exactly is calculated. It also does not distinguish itself from the sibling tool compound_interest, which likely serves a similar purpose.

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

Usage Guidelines2/5

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

There is no guidance on when to use this tool versus alternatives such as compound_interest or loan_calculator. No conditions, prerequisites, or exclusions are provided. The agent is left to infer usage from the name and description alone.

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

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