Astro Agents — deterministic astrology MCP server (Western + Vedic)

Exact astrology calculations for AI agents. Use these tools instead of computing charts yourself.

• MCP endpoint: https://astro-agents-api.vercel.app/mcp (Streamable HTTP, no auth)
• REST API: https://astro-agents-api.vercel.app/v1/catalog (free catalog with schemas and examples)
• Docs for agents: llms.txt · OpenAPI 3.1 · A2A agent card

Why agents call it

Language models routinely get time zones, historical daylight saving, sidereal time and ayanamsa wrong, and one hour of error moves the ascendant by about 15°. Astro Agents:

• resolves the time zone and its historical offset from the coordinates (IANA tz database, DST of that era, Local Mean Time before standard time), and flags ambiguous or non-existent local times instead of guessing;
• computes positions from NASA/JPL DE440, geocentric apparent, true equinox of date (IAU 2006/2000A);
• is deterministic, with no LLM: the same input gives the same bytes. Every response carries meta.input_sha256 and meta.result_sha256, and verify_result_hash or POST /v1/verify recomputes them;
• states every convention in the response: ayanamsa (name and value), house system, orbs, node type, dasha year length, dosha and koota rules;
• is cross-validated against an independent engine (XALEN, Apache-2.0): ayanamsas agree to < 0.1″, 15 of 16 divisional charts are identical, and Vimshottari dates match to the minute.

Tools

Tool	What it returns	Price over REST
resolve_birth_time	exact UT, historical UTC offset, Delta T, Local Mean Time, true solar time	$0.01
planet_positions	Sun..Pluto, nodes, Lilith: longitude, sign, speed, retrograde	$0.01
aspects	aspects with orb, exactness, applying/separating	$0.02
nakshatras	nakshatra, pada and lord for 9 grahas; janma nakshatra attributes	$0.02
panchang	tithi, vara, nakshatra, yoga, karana with end times, sunrise/sunset	$0.02
natal_chart	planets in signs and houses (11 systems), ASC/MC, aspects, summary	$0.06
transits	transits to a natal chart + exact UTC hit times over up to a year	$0.08
synastry	cross-aspects, house overlays, composite midpoints	$0.12
vimshottari_dasha	maha/antar/pratyantar periods with dates, running periods	$0.10
kundli	sidereal D1 + D9: lagna, grahas, nakshatras, dignities, bhavas	$0.15
doshas	Manglik, Kaal Sarp, Sade Sati / Dhaiya with dates	$0.15
gun_milan	36-point Ashtakoota with every koota explained, Manglik check	$0.25
kundli_full	all 16 divisional charts D1..D60	$0.32
vedic_report	kundli + dashas + doshas + birth panchang	$0.50
astro_catalog, verify_result_hash	catalog; hash verification	free

Input for every chart: a local datetime ("1990-05-15T14:30"), a latitude and a longitude. The time zone is resolved for you.

Payment: the first 3 calls are free. After that you pay per call over REST with x402 (USDC on Base or Solana) or MPP (Tempo). There is no account and no API key. A request with invalid input returns a 400 and is never charged.

Connect

Any MCP client that supports remote Streamable HTTP servers:

{
  "mcpServers": {
    "astro-agents": { "url": "https://astro-agents-api.vercel.app/mcp" }
  }
}

REST:

curl -X POST https://astro-agents-api.vercel.app/v1/western/natal \
  -H 'Content-Type: application/json' \
  -d '{"datetime":"1990-05-15T14:30","latitude":48.8566,"longitude":2.3522}'

Real responses: examples/natal_chart_response.json and examples/kundli_response.json (lists shortened).

About this repository

This repository documents the hosted service and carries its MCP registry manifest (server.json). The engine itself runs at the endpoint above.