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Developer & Agent Resources

BoringToolsKit is a free collection of private, no-signup browser calculators and everyday tools for money, home, school, and work — built for anyone who wants instant answers without accounts or uploads.

This page documents the machine-readable surfaces so AI agents and developers can discover and use the calculators programmatically. The same endpoints are listed in llms.txt.

MCP server

BoringToolsKit MCP server — a Model Context Protocol (Streamable HTTP) endpoint that exposes the calculators as callable tools so an agent can compute a result directly.

Endpoint: https://boringtoolskit.com/mcp (POST JSON-RPC 2.0)
Transport: Streamable HTTP
Capabilities: tools
Server card: /.well-known/mcp/server-card.json

# Discover tools
POST /mcp
Content-Type: application/json

{"jsonrpc":"2.0","id":1,"method":"tools/list"}

# Call a tool
POST /mcp
Content-Type: application/json

{"jsonrpc":"2.0","id":2,"method":"tools/call",
 "params":{"name":"mortgage_payment","arguments":{"price":300000,"down":60000,"term":30,"apr":6.5}}}

Available tools

Tool	What it computes
`tip_bill_split`	Split a bill across a group after tax, tip, and optional rounding.
`discount_percent_off`	Final checkout total after stacked discounts, coupon, and tax.
`bmi`	Body mass index and category from weight and height.
`bmr_tdee`	BMR (Mifflin-St Jeor) and total daily energy expenditure.
`mortgage_payment`	Monthly housing payment (P&I, tax, insurance, PMI, HOA) and total interest.
`auto_loan`	Monthly auto-loan payment from price, down, trade, term, and APR.
`compound_interest`	Compound growth with optional monthly contributions.
`savings_growth`	Future value of a lump sum with optional monthly additions.
`simple_interest`	Simple interest, total value, and compound comparison.
`calorie`	BMR and total daily energy expenditure (Mifflin-St Jeor).
`percentage`	Percentage problems: of, is-what, and change.
`square_footage`	Area with waste plus square yards, square metres, and acres.

Quickstart

Connect an MCP-compatible client to the endpoint and list the tools, then call one.

# 1. Connect (any MCP client)
#    name: boringtoolskit
#    url:  https://boringtoolskit.com/mcp
#    transport: streamable-http

# 2. List the tools
POST /mcp
{"jsonrpc":"2.0","id":1,"method":"tools/list"}

# 3. Compute a result
POST /mcp
{"jsonrpc":"2.0","id":2,"method":"tools/call",
 "params":{"name":"bmi","arguments":{"weightLb":180,"heightFt":5,"heightIn":10}}}
# => {"bmi":25.8,"category":"Overweight"}

No API key is required. The calculators are public and read-only; any input you send is used only to compute that response and is never stored.

Machine-readable resources

llms.txt
Overview plus links to every tool, hub, and machine-readable file.

llms-full.txt
Complete catalogue with authored formulas, assumptions, and sources.

tool-knowledge.json
Evidence-labeled records generated from the live catalogue and authored methodology.

/.well-known/mcp/server-card.json
MCP server card describing the endpoint, transport, and tools.

/.well-known/agent-skills/index.json
Agent-skills discovery manifest (v0.2.0) listing BoringToolsKit capabilities.

sitemap.xml
Complete URL inventory for crawling.

Data files

/assets/tool-index.json
Tool index with slugs, names, paths, families, and tiers.

/assets/converter-index.json
Converter units and factors (length, weight, temperature, and more).

state-tax-rates.json
State income-tax rate data used by the paycheck tools.

Versioning & deprecation policy

Agents should rely on a stable surface. BoringToolsKit follows these conventions:

Surface	Version signal	Compatibility
MCP server `/mcp`	`serverInfo.version` in `initialize` (currently `1.0.0`)	Semantic version; a new minor adds tools, a major may change tool schemas.
Tool schemas	`tools/list` input schemas	New optional input properties are additive; never removed in a minor release.
Data files	File format is documented in `llms.txt` and `tool-knowledge.json`	Additive field growth; breaking changes bump the file's schema version.

Deprecation: when a tool or field is retired it is announced here and in llms.txt, kept functional for a deprecation window, then removed. A Sunset header is returned on any deprecated endpoint during that window so clients can detect it without probing.

How agents should use these

Start with llms.txt to learn the catalogue, then use the MCP server (/mcp) to compute a specific result. For methodology, formulas, and assumptions behind a result, read the authored content in llms-full.txt or the per-tool methodology section on each page.

Adopt tool-knowledge.json when you need a structured, evidence-labeled record of every tool in one file.