12 min read·
AGENTS.md for API Providers: Teach AI Coding Tools to Use Your API
How to ship an AGENTS.md in your API SDK so Copilot, Windsurf, Cline, and Claude Code call your endpoints correctly. By RoxyAPI.
Brett Calloway
Developer Advocate & AI Integration Specialist
United States
Brett Calloway has 12 years of experience building APIs and developer tooling, including three years focused on AI-native infrastructure for spiritual and wellness applications. He writes on building context-rich AI agents using Model Context Protocol, drawing on a developer relations background. His coverage spans API integration patterns, AI agent architecture, and rapid prototyping with astrology, tarot, and numerology data.
12 years in API developmentDeveloper relations backgroundWriting on AI agents and MCP
API integrationAI agentsModel Context ProtocolDeveloper toolsAstrology APIMCP
43 articles published
Articles by Brett Calloway
9 min read·
Biorhythm API: What It Is, How It Works, and How to Use It
A biorhythm API calculates physical, emotional, and intellectual cycles from a birth date. Learn how it works and how to integrate it.
9 min read·
Zodiac Sign API: Birthdate to Full Profile in 5 Minutes
Turn any birthdate into a zodiac sign, natal chart, daily horoscope, and compatibility score. Four endpoints, one API key, five minutes.
9 min read·
How to Verify Astrology Software Against NASA JPL
Learn to verify astrology accuracy using NASA JPL Horizons as ground truth. Step-by-step guide with tolerance thresholds, common errors, and automated testing.
10 min read·
Swiss Ephemeris AGPL Licensing for SaaS Developers
Swiss Ephemeris AGPL license requires SaaS apps to open source their entire codebase. Learn your options and AGPL-free alternatives for astrology APIs.
13 min read·
How to Evaluate a Tarot API: Developer Checklist 2026
A 10-point checklist to evaluate tarot APIs on card coverage, spread support, reproducibility, AI readiness, and pricing before you commit.
15 min read·
AI Astrology API vs Calculation Infrastructure: 375x Gap
AI wrapper astrology APIs charge $0.15 per query. GPT-4o-mini costs $0.0004 for the same result. 375x markup exposed with full pricing math. By RoxyAPI.
12 min read·
Real Cost of Multi-Domain Spiritual APIs: One Key vs Nine (2026)
Astrology API pricing comparison with real math. 9 domains for $4.33 each vs $84 to $200 per month from separate providers. Flat rate beats wallet pricing.
11 min read·
How to Evaluate an Astrology API Before You Build On It
A 10-point checklist for evaluating astrology APIs covering accuracy, pricing, SDK support, MCP tools, and production readiness.
10 min read·
Connect RoxyAPI to Wix Studio Using Velo
Learn how to call RoxyAPI astrology and tarot endpoints from Wix Studio using Velo backend web modules and wix-fetch.
12 min read·
Create a Custom Astrology GPT with No Code Using GPT Actions
Build a custom ChatGPT GPT that reads horoscopes, draws tarot cards, and calculates natal charts using GPT Actions and RoxyAPI.
11 min read·
Build an Astrology Birth Chart App on Bubble with No Code
Step by step guide to building a natal birth chart app on Bubble using the API Connector and RoxyAPI. No coding required.