Jackpot Calculator MCP

Compare cash and annuity

compare_lump_sum_annuity

Read-onlyIdempotent

Compare a published lottery cash option with 30 growing annuity payments after taxes, including present value and break-even rate to decide which payout fits your financial plan.

Instructions

Compare a published cash option with 30 growing annuity payments after taxes, including present value and break-even rate.

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": {
      "jackpot": "<jackpot>",
      "cashValue": "<cashValue>",
      "stateCode": "<stateCode>"
    },
    "name": "compare_lump_sum_annuity"
  }
}

Input Schema

Name	Required	Description	Default
`game`	No		custom
`status`	No		single
`jackpot`	Yes	Advertised annuity total in US dollars.
`winners`	No	Number of jackpot-winning tickets sharing the prize.
`locality`	No	Only valid with stateCode NY.
`cashValue`	Yes	Published cash option in US dollars; do not infer it from a fixed ratio.
`stateCode`	Yes	US residence and ticket-purchase state, two-letter code. Cross-state claims are not modeled.
`otherIncome`	No	Other annual income in US dollars before the standard deduction.
`discountRate`	No	Annual discount rate as a fraction, e.g. 0.04 for 4%.
`sharePercent`	No	Your percentage of one winning ticket.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 12, 2026

TDQS

B3.3/5.0

Behavior3/5

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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds useful behavioral context that the computation is after-tax, assumes 30 growing payments, and returns present value and break-even rate. It does not disclose tax-jurisdiction assumptions or result format, so it is modest value on top of annotations.

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

Conciseness5/5

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

A single front-loaded sentence that names the comparison, the tax basis, the payment structure, and the outputs with zero filler. Nothing is wasted and the core action leads the sentence.

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

Completeness3/5

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

With 10 parameters and no output schema, the description partially compensates by naming the returned figures (present value, break-even rate). However, it omits usage context, the tax-state modeling behavior, and any note on the many optional inputs, leaving gaps for a fairly complex financial tool.

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 80%, so the schema already documents jackpot, cashValue, stateCode, and others well. The description names no parameters and adds no syntax, units, or constraint meaning beyond the schema, so the baseline 3 applies.

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?

States a specific verb (compare) and the two resources being compared (published cash option vs. 30 growing annuity payments after taxes), plus the resulting metrics. An agent can tell this is the cash-vs-annuity decision tool, distinct from the odds/payout/pool-share siblings, though the description never names a sibling to reinforce the distinction.

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?

The description describes what the tool computes but gives no when-to-use guidance, no mention of alternatives, and no prerequisites. Nothing tells the agent to reach for this over calculate_lottery_payout, nor under what conditions it should be chosen.

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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