Control structure and cost on the same path.
Last updated 29 August 2026
Hexum is MCP for coding agents: smaller context and deterministic architecture gates. Connect once. Keep the editor.
What you notice
The agent still opens what it should. The model still has enough to ship a patch. You are not paying to reprint the repo every turn. Measured context cuts: about 85% on MBPP and 89% on HumanEval, same tests passing. Method: how MBPP and HumanEval were run.
What you keep
Cursor, Claude Code, Antigravity, Codex, or Grok. Git. Your models.
Hexum sits on that path as a hosted server at https://hexum.dev/mcp. It does not merge, commit, or push.
What Hexum is not
Not an IDE. Not a customer CLI. Not a model. Not a store of your repo (Zero Data Retention). Standalone extract: What is Hexum.
hexum_shrink hexum_check architecture.hexum MCP install
FAQ
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 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.
How does Hexum reduce tokens?
The agent calls hexum_shrink before it reads widely. The model is sent this turn, not the repository. On MBPP, measured context dropped about 85% with the same tests passing. Example turn: 18.2k → 3.1k tokens, 41 files → 6. See /benchmarks and /methodology.
Is hexum_check an LLM?
No. hexum_check is deterministic. It maps files to layers in architecture.hexum and reports forbidden imports. It does not call a model.
How is Hexum billed?
Hexum bills tokens saved: input minus what still goes to the model. Cache hits are free. No monthly cap. No seat tax. Usage early access from €0.30 per million. Teams from €0.35 per million. See /pricing.
What is tokens saved?
Tokens in minus tokens out, when that is positive. Stripe is billed on tokens saved. Calls that do not save tokens still increment calls and the in/out counters.
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.
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.