Effective Rate (APR <-> APY)

Convert a nominal rate to effective annual yield, or back, at any compounding frequency.

Free tier eligible — 500 calls/month with a free key from /pricing; x402 pay-per-call above quota.

Parameters

Parameter	Type	Required	Description
`mode`	string	optional	Direction One of: to_apy, to_apr
`apr`	number	optional	Nominal annual rate as a decimal (to_apy)
`apy`	number	optional	Effective annual yield as a decimal (to_apr)
`periods`	number	optional	Compounding periods per year, or 'continuous' (default 12)

Call it over MCP (JSON-RPC 2.0)

curl -s https://wingmanprotocol.com/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": {"name": "effective_rate", "arguments": {"mode": "to_apy", "apr": 0.07, "apy": 100}}}'

Or plain HTTP

curl -s https://wingmanprotocol.com/tools/effective_rate \
  -H 'Content-Type: application/json' \
  -d '{"mode": "to_apy", "apr": 0.07, "apy": 100}'

Try it live

Edit the JSON and run it — this POSTs to https://wingmanprotocol.com/tools/effective_rate from your browser.

This tool is x402-metered — agents pay per call with USDC on Base. The 402 response below is the standard x402 payment-requirements envelope: sign the EIP-3009 authorization and retry with the X-Payment header, or get a free key at /pricing (500 calls/month, no card, no crypto).