Dev error explainers MCP server

dev-error-explainers

Paste an error. Get a deterministic explanation.

No LLM · no API · no network · no telemetry

npm run build 2>&1 | npx dev-error-explainers

npm install dev-error-explainers

import { detect, explainEsmCjs } from 'dev-error-explainers';
const error = 'Error [ERR_REQUIRE_ESM]: require() of ES Module /app/node_modules/node-fetch/src/index.js from /app/index.js not supported.';
console.log(detect(error));
const { findings } = explainEsmCjs({ error, nodeVersion: '20.10.0' });
console.log(findings[0].title, findings[0].fixes.map((f) => f.title));

Output:

[ 'esm-cjs-explainer' ]
ERR_REQUIRE_ESM — require() of an ES module [
  'Upgrade Node.js (you are on 20.10.0)',
  'Use dynamic import() from CommonJS',
  'Convert the calling file to ESM'
]

Seven small, pure JavaScript modules with zero dependencies. Each one recognises the exact error text a developer pastes (from the browser console, npm, next build, curl -I, a Node.js stack trace…), explains why it happens, and returns concrete fixes with a link to the primary source where one exists (MDN, the Node.js docs, the npm docs, the PostgreSQL docs, the Supabase docs…). The same engine runs as a library, a CLI, a GitHub Action and an MCP server.

Secrets: the CLI, the Action and the MCP server pass the input through redact() before it is analysed, with one exception: the DATABASEURL doctor reads the raw postgres:// line (a password's exact characters decide the diagnosis), and never prints that password. Used directly as a library, six of the seven modules mask what looks like a secret before echoing it back; the build-error decoder does not** — it quotes the matching lines of your build output as they are. Redaction has limits: see what it does not catch.

Six of them power the free tools on iloveblogs.blog/tools, where you can try each one in the browser.

Shortened. The full README is on GitHub.