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MCP Is Not Good Yet — David Cramer, Sentry
Takeaway
MCP is a useful plug-in architecture for agents but you must design tool surfaces for LLMs, not just wrap your existing API — and OAuth on remote MCP is the only sane path for B2B SaaS.
Summary
- Sentry's founder built their MCP server in a few days; argues remote MCP (not stdio) is the relevant interface for B2B SaaS
- Hot take: MCP is a pluggable architecture for agents — not a thing to bolt on top of OpenAPI. Re-exposing API endpoints as tools produces 'the worst results you can possibly imagine'
- OAuth 2.1 with dynamic client registration is awkward; Sentry used Cloudflare's OAuth shim to proxy their OAuth2 API onto Cloudflare Workers
- Client support is uneven: VS Code Insiders works well, Cursor promised native OAuth, Claude/Claude Code partial — read-only mode/hint annotations underused by clients (only ~17% of Sentry's users)
- Demo: VS Code Insiders + Sentry MCP made 20 API calls and started fixing bugs (cost ~$5) — context delivery is what matters, fix quality is secondary today
mcpoauthsentry
Original description
You’ve heard a lot about MCP, probably been given an AI mandate or two, and are trying to figure out what’s real and what’s make believe. This session will give practical advice for how you should be thinking about MCP, the implementation pit falls, and where the speaker thinks things are going. ---related links--- https://twitter.com/zeeg https://cra.mr https://sentry.io