Overview & result
Jev Tool Router exposes a small MCP discovery surface to Codex. Jev sees a requested capability plus tool names and descriptions, chooses a tool only above the default 0.90 threshold, and otherwise returns a compact shortlist with search and pagination fallbacks.
From the original post
Jev-powered MCP tool routing for Codex.
Instead of exposing hundreds of external MCP tool schemas directly to the agent, Jev Tool Router exposes a small routing surface and resolves external tool discovery on demand.
How Jev fits in the loop
- Receive the agent's requested capability and optional task context.
- Ask Jev to choose among tool names and descriptions, including none_of_the_above.
- Return one tool and schema only when its probability clears the configured threshold.
- On uncertainty or error, return a compact shortlist and allow targeted search or paginated expansion.
How to reproduce
- Inspect the source implementation at https://github.com/jackbarunz/jev-tool-router.
- Configure local Jev API credentials and register required tool/model bindings.
- Execute test prompts and observe decision latency and routing outputs.
Why this build matters
Demonstrates bounded tool discovery without hiding the full inventory or claiming unmeasured savings.
Limitations
- Unofficial community project, not affiliated with TypeSafe, Vercel or OpenAI.
- Automatic setup covers external MCP servers configured under Codex mcp_servers; built-in Codex tools stay native.
- A tool is selected only when its probability reaches the configured threshold; otherwise the agent gets a lexical shortlist to refine.