MIT open-source software
US$0 software licenceSelf-hosted; provider usage charged separatelyInstall the local MCP server or hook. Jev routing uses your OpenRouter API key; this is not an included hosted-model subscription. Official source 1 ↗
Website-checked tool profile
Harness Router
An open-source tool-selection layer for AI agents, with MCP routing and optional local search.
Sources checked
- Pricing
- The software is open source under MIT. Jev-based routing requires the user’s OpenRouter key, so model usage is separate from the software licence; the site advertises Jev input at US$0.042 per million tokens and free output tokens. Official source 1 ↗
- Available as
- The site documents integrations for Codex, Claude Code, ohmypi, Antigravity and DeepSeek Harness, plus a native stdio MCP server; the hook installer requires Python 3.11 or later. Official source 1 ↗
- Primary group
- Automation & Agents
What it does
Harness Router is an MIT-licensed tool-selection layer for AI coding agents. It uses a skill, pre-execution hook or MCP tools to route a shortlist of actions, with optional Jev-backed search for ambiguous decisions.
Official source 1 ↗Features
- Closed-choice action routing. The route MCP tool accepts a compact goal, latest observation and shortlist, and returns a structured selection. Official source 1 ↗
- Pre-execution checks. A hook validates a proposed tool call against the discovered tool inventory before execution. Official source 1 ↗
- Local search after a model prior. route_mcts searches a supplied side-effect-free graph; Jev can seed the root once while remaining simulations run locally. Official source 1 ↗
- Replanning without changing approvals. A confident alternative can block one call and request replanning; existing sandbox and approval rules remain in place. Official source 1 ↗
Pricing & free limits
Billing details
Jev routing needs an OpenRouter API key when route is called; the server itself can load without the key. Official source 1 ↗
Free access & limits
The MIT software is open source; hosted model usage is not established as a free allowance and requires your provider key. Official source 1 ↗
Best for & limitations
Add a routing check to a coding agent that has several plausible tools available, returning one choice for the agent’s broader execution loop. Official source 1 ↗
- Search needs a supplied graph. Automatic MCTS escalation requires a side-effect-free graph provider; the hook does not invent a graph when none is configured. Official source 1 ↗
- Fails open on routing errors. Fallbacks, timeouts and router errors allow the original tool call to continue. Official source 1 ↗
- Selection is not execution. Simulated writes, shell commands and browser or network mutations are not executed by the search server; it selects the first action. Official source 1 ↗
