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[MCP] Vercel MCP not supported - OpenCode not in approved clients list #27761
Description
Description
Vercel MCP is not working in OpenCode. Even with a valid API token configured, the server returns an authentication error.
According to the official Vercel MCP documentation, Vercel maintains a whitelist of approved MCP clients and OpenCode is not on the list. Clients like Claude Code, Cursor, ChatGPT, etc. are supported, but OpenCode is not recognized even when using a valid Full Account Access token.
Error received:
{"jsonrpc":"2.0","error":{"code":-32000,"message":"Not Acceptable: Client must accept both application/json and text/event-stream"},"id":null}
Reference: https://vercel.com/docs/agent-resources/vercel-mcp
Plugins
vercel (MCP)
OpenCode version
[latest, updated 2026-05-15] 1.15.0
Steps to reproduce
- Generate a Vercel API token at https://vercel.com/account/tokens with Full Account Access scope
- Configure the token in opencode.json under mcp.vercel.headers
- Restart OpenCode
- Try to use any Vercel MCP tool
- Authentication error occurs
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N/A
Operating System
Windows 11
Terminal
Warp (powershell)
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github-actions commentedon May 15, 2026
This issue might be a duplicate of an existing issue. Please check:
Accept: application/json, text/event-streamheader, resulting in the identical error message:Not Acceptable: Client must accept both application/json and text/event-stream. That issue covers Context7 but the underlying fix (adding the Accept header) would likely resolve Vercel MCP connectivity as well.rekram1-node commentedon Jun 9, 2026
we aren't in the docs for whatever reason but vercel mcp does work in opencode:
opencode mcp auth vercel
-> opencode
It works just tested