One install. Every agent.

Last updated 29 August 2026

Install Hexum MCP in Cursor in 3 steps

Open /app, turn usage billing on, mint a hexum_live_ key.
Paste this JSON into the agent’s MCP config (Cursor Settings → MCP, or the command on Hexum for Claude Code).
Reload MCP. The agent lists tools from tools/list.

mcp.json

{
  "mcpServers": {
    "hexum": {
      "serverUrl": "https://hexum.dev/mcp",
      "headers": { "Authorization": "Bearer hexum_live_…" }
    }
  }
}

Per-agent pages

Hexum MCP for Cursor — Cursor Settings → MCP, or paste the JSON into ~/.cursor/mcp.json, then reload.
Hexum for Claude Code — From a terminal in the project: claude mcp add --transport http hexum https://hexum.dev/mcp --header "Authorization: Bearer hexum_live_…"
Hexum MCP for Antigravity — Open MCP servers in Antigravity. Add a remote HTTP server with the mcpServers JSON, then reload.
Hexum MCP for Codex — codex mcp add hexum --url https://hexum.dev/mcp --header "Authorization: Bearer hexum_live_…" then codex mcp list.
Hexum MCP for Grok — grok mcp add --transport http hexum https://hexum.dev/mcp --header "Authorization: Bearer hexum_live_…"

Optional: skill full in architecture.hexum. The agent calls hexum_skill and writes the Hexum skill.

Get API key

FAQ

How do I add Hexum to Cursor?

Turn on usage billing at /app, mint a hexum_live_ key, paste the mcpServers JSON into Cursor Settings → MCP or ~/.cursor/mcp.json, then reload. Details: /cursor.

Does Hexum replace Cursor or Claude Code?

No. Hexum is a hosted MCP server. You keep Cursor, Claude Code, Antigravity, Codex, or Grok. Hexum is not an IDE and not a model.

Why did MCP return BILLING or AUTH?

AUTH means the key is missing, invalid, or revoked. BILLING (HTTP 403) means that key’s billing source is off: personal Usage for a personal key, or Teams billing for a team key. Turn the matching plan on at /app, or mint a key against the plan that is on.

What is Hexum?

Hexum is an MCP server for Cursor, Claude Code, and other coding agents. It sits between the agent and the model: hexum_shrink sends this turn instead of the repository, hexum_check fails the turn when architecture.hexum is broken, and you keep your editor. On MBPP, context dropped about 85% with the same tests passing.

Does Hexum store my repo?

No. Zero Data Retention is on Usage and Teams. MCP payloads are not stored. Hexum does not train on your code. Policy: /zdr.