Sign up, get your API key, connect via MCP. Your AI agent gets 209 precision math methods and a curated knowledge base of 981 entries — exact arithmetic, exact radical trig, deterministic results, no hallucination. Works with Claude, ChatGPT, Cursor, Windsurf, and any MCP client.
https://arithym.xyz/mcp as a remote MCP server. You'll be prompted to authorize with your email — no API key needed, no config files. OAuth handles everything automatically.
Pick a tier on the pricing page, enter your email, and accept the Terms of Service. You'll receive your API key — a string starting with mc_free_, mc_pro_, or mc_eng_.
Claude Desktop — Edit claude_desktop_config.json:
{
"mcpServers": {
"arithym": {
"url": "https://arithym.xyz/mcp",
"headers": {
"Authorization": "Bearer YOUR_API_KEY"
}
}
}
}
Replace YOUR_API_KEY with the key from Step 1. Restart Claude Desktop.
Claude.ai — Connect via Settings → Connectors:
https://arithym.xyz/mcp
ChatGPT — Go to Settings → Connectors (or Apps) → Add custom connector:
# Server URL https://arithym.xyz/mcp # Authentication OAuth (automatic via authorize page)
Cursor / Windsurf / Other MCP clients — Add as a remote server:
# Server URL https://arithym.xyz/mcp # Transport SSE # Header Authorization: Bearer YOUR_API_KEY
https://arithym.xyz/mcp instead.
Once connected, your agent has a complete precision math engine — 209 methods across 22 domains, backed by 981 curated reference entries from CODATA 2022, IUPAC 2021, and SI definitions. Try these to confirm your connection works:
compute("12847", "93", "multiply")
factorize("48620")
fraction_math("0.1", "0.2", "add")
scratch_math([["multiply","99.95","1.0825"], ["multiply","$prev","3"]])
Epithreads knowledge base — 981 curated entries with 2,454 searchable names and aliases. Look up constants, elements, materials, trig values, and conversion factors:
reference action=lookup query="speed of light"
reference action=lookup query="Fe"
unit_factor("psi", "kPa")
guide_call("chemistry", "molar_mass", '["C6H12O6"]')
Arithym v6.2 is a precision math engine that routes to 209 exact-math methods across 22 domain modules, backed by the Epithreads knowledge base (981 curated entries). Your agent can call help() for a system overview, discover("keyword") to search all 209 methods, or recommend("describe your problem") to get the optimal tool suggestion.
What's New in v6.2
Transcendental graph operations — sin, cos, tan, log, exp, and abs as graph node ops. Build physics simulations, signal processing, and optimization models. Autodiff through all 6 ops.
Transcendental graph operations — sin, cos, tan, log, exp, and abs as graph node ops. Build physics simulations, signal processing, and optimization models. Autodiff through all 6 ops. 5-second computation budget per request.
Exact radical trig — sin(45°) = √2/2, cos(30°) = √3/2, sin(15°) = (√6−√2)/4. Special angles resolved via Epithreads radical lookup — fully exact, zero floats.
Epithreads knowledge base — 981 curated entries: CODATA 2022, IUPAC 2021, SI definitions, engineering materials, exact trig. All queryable by name, symbol, or alias.
Hybrid precision model — Algebraic operations (arithmetic, fractions, GCD, power, etc.) are exact — zero floating-point error. Transcendental functions (sin, cos, tan, log, exp) in computational models use IEEE 754 double precision (15 significant digits), with results flagged as precision: "IEEE 754 double" and sig_figs: 15. Every result carries its precision status.
Navigation — help, domain_check, discover, recommend, guide_call
Arithmetic — compute, factorize, fraction_math, exact_sqrt, rational_sqrt, exact_trig
Multi-step — scratch_math, scratch_math_units, slide
Workspace — field_create, field_add, field_read, field_derive, field_update, field_sensitivity_all, field_optimize
Compute graphs — graph_define, graph_forward, graph_sensitivity, graph_solve, graph_what_if, graph_learn. Graph ops: add, subtract, multiply, divide, power, gcd, lcm, product, sin, cos, tan, log, exp, abs
Calculus — graph_derivative, graph_gradient, graph_jacobian, graph_hessian, graph_taylor, graph_integral, graph_critical_points
Units — unit_factor, unit_check, list_units
Reference (Epithreads) — lookup, query_entries, list_entries, db_stats — 981 entries: CODATA 2022 constants, IUPAC 2021 elements, exact unit conversions, formulas, material properties, exact trig
22 domain modules via guide_call — arithmetic, fractions, roots, trig, matrix, statistics, calculus, chemistry, physics, finance, geometry, signals, complex, number theory, algebra, medical, materials, quantum, scientific, verification, units, sphere-spiral
Usage is tracked per API key. Both MCP and REST endpoints share the same daily counter.
Limits reset at midnight UTC. If you hit your limit, the server returns a 429 status. Upgrade anytime on the pricing page.
All requests require a Bearer token in the Authorization header. This is your API key from Step 1.
# HTTP header (set in your MCP client config)
Authorization: Bearer mc_free_aBcDeFgH...
Invalid or missing keys receive a 401 Unauthorized response. Deactivated keys receive 403. Rate-limited keys receive 429 with a Retry-After header.
Questions, bugs, or feature requests — email jacob@arithym.xyz.
For detailed tool documentation once connected, call help("tool_name") from your agent. Every tool has a built-in usage guide with examples, parameter descriptions, and routing advice.