@modelcontextprotocol/hono@2.0.0
Release 2.0.0 of @modelcontextprotocol/hono introduces initial SDK v2 beta support for the 2026-07-28 specification revision, dual ESM/CJS builds, and stricter Content-Type validation returning 415 for non-JSON POST requests.
Why this signal matters
@modelcontextprotocol/hono@2.0.0 marks the first beta release of SDK v2 with support for the MCP 2026-07-28 specification revision. The release ships CommonJS builds (.cjs/.d.cts) alongside ESM (.mjs/.d.mts) with package exports configured for require() support. Additionally, Content-Type validation for POST requests has been updated to parse the media type rather than relying on substring matching; requests lacking an application/json media type now return 415 Unsupported Media Type. A new helper, isJsonContentType(header), is exported for custom transport and adapter authors. Dependency @modelcontextprotocol/server was updated to 2.0.0.
Actionable summary
@modelcontextprotocol/hono@2.0.0 released with MCP 2026-07-28 spec support, dual ESM/CJS exports via tsdown, and stricter Content-Type parsing rejecting non-application/json POSTs with 415 Unsupported Media Type. Exports isJsonContentType helper.
- Agent usefulness
- 82/100
- Confidence
- 96%
- Canonical data
- JSON + Markdown
What builders should check
- Consult the v1-to-v2 upgrade guide (docs/migration/upgrade-to-v2.md) and the 2026-07-28 specification adoption guide (docs/migration/support-2026-07-28.md).
- Ensure client POST requests include a valid Content-Type header matching application/json to avoid 415 Unsupported Media Type responses.
- Adopt the exported isJsonContentType(header) helper if authoring custom framework adapters or transports using classifyInboundRequest or PerRequestHTTPServerTransport.