Content
# CalcFleet MCP Server
**121 deterministic, source-cited calculators as MCP tools — the math your AI agent can call instead of hallucinating.**
CalcFleet is a hosted [Model Context Protocol](https://modelcontextprotocol.io) server. Instead of letting a language model guess at compound interest, loan amortization, take-home pay, or LLM self-host-vs-API breakeven, your agent calls a CalcFleet tool and gets the exact number back — the same tested, Zod-validated math that powers [calcfleet.com](https://calcfleet.com).
- **Deterministic.** Identical inputs always produce identical outputs. The model never does the arithmetic.
- **Source-cited.** Every result includes a `provenance` block: the canonical tool URL, the sources behind the formula, and a data vintage where applicable.
- **Validated.** Every input is checked against strict numeric bounds; invalid input returns a structured error, never a silent wrong answer.
- **No account, no data collection.** Free during launch.
Web version, REST API, and full docs: **https://calcfleet.com** · MCP landing: **https://calcfleet.com/mcp**
---
## Quick start
The server is remote (Streamable HTTP) — no install, just point your client at the URL.
### Claude Desktop
```json
{
"mcpServers": {
"calcfleet": {
"url": "https://calcfleet.com/api/mcp"
}
}
}
```
### Any MCP client (generic)
```json
{
"mcpServers": {
"calcfleet": {
"url": "https://calcfleet.com/api/mcp",
"transport": "streamable-http"
}
}
}
```
Tool names are the site slugs with dashes as underscores (e.g. `compound_interest_calculator`). New calculators added to the fleet appear as MCP tools automatically.
---
## Example tool calls
**Compound interest** — `compound_interest_calculator`
```jsonc
// input
{ "initialPrincipal": 10000, "monthlyContribution": 500, "annualRatePct": 7, "years": 20 }
// result
{ "finalBalance": 300850.72, "totalContributed": 130000, "totalInterest": 170850.72, ... }
```
**Self-host vs API for LLMs** — `llm_self_host_vs_api_calculator`
```jsonc
// input
{ "monthlyInputTokensM": 100, "monthlyOutputTokensM": 20, "apiModelId": "claude-sonnet-4.6",
"gpuId": "h100-sxm-80gb", "gpuHourlyUsd": 3.99, "throughputTokensPerSec": 20000, "utilizationPct": 50 }
// result
{ "apiMonthlyCost": 600, "selfHostMonthlyCost": 2872.8, "breakevenTokensM": 574.56, "cheaper": "api", ... }
```
Every result is returned as `{ "result": {...}, "provenance": {...} }`, where `provenance` carries the sources and data vintage so your agent can cite where the numbers came from.
---
## What's inside — 121 tools across 15 categories
| Category | Tools | Examples |
|---|---|---|
| Business & Startups | 20 | break_even, margin_markup, cac_ltv, saas_mrr_growth |
| Home & Renting | 19 | rent_vs_buy, paint, flooring, tile, solar_panel_savings |
| Savings & Investing | 13 | compound_interest, fire, roth_ira, retirement_monte_carlo |
| AI & LLM Economics | 13 | llm_self_host_vs_api, ai_agent_cost, rag_cost, fine_tuning_cost, gpu_vram |
| Auto Loans | 8 | car_loan, lease_vs_buy_car, car_depreciation, cost_per_mile |
| Fitness & Nutrition | 8 | tdee, macro, body_fat, calorie_deficit |
| Mortgage & Home Loans | 7 | mortgage_overpayment, mortgage_piti, home_affordability |
| Cooking & Kitchen | 6 | recipe_scaler, pizza_dough, baking_pan_conversion |
| Loans & Financing | 5 | loan_amortization, personal_loan, dti, heloc |
| Salary & Take-Home Pay | 5 | take_home_pay, salary_to_hourly, overtime_pay |
| Photography | 5 | depth_of_field, crop_factor, print_resolution |
| Pet Ownership | 5 | dog_age, pet_food_portion, puppy_weight |
| Debt & Credit | 4 | debt_payoff, credit_card_payoff, debt_consolidation |
| Freelance & Self-Employed | 2 | freelance_rate, contractor_vs_employee |
| Sport & Training | 1 | running_pace |
There is also a **calculation graph** endpoint (`POST /api/v1/graph`, REST) that composes several calculators into one deterministic DAG — for agents that need a multi-step plan in a single call.
---
## Also available
- **REST API** — `POST /api/v1/tools/{slug}` · docs at https://calcfleet.com/developers
- **OpenAPI spec** — https://calcfleet.com/api/openapi
- **llms.txt** — https://calcfleet.com/llms.txt
## Registry
Published on the official MCP Registry as [`com.calcfleet/calculators`](https://registry.modelcontextprotocol.io/v0/servers?search=com.calcfleet).
## License
MIT — see [LICENSE](./LICENSE). (This repository is documentation for the hosted CalcFleet MCP server; the calculator implementations run on calcfleet.com.)
