Known Issues
This file tracks limitations that users regularly run into. Most of these require upstream cooperation or larger refactors—feel free to reference this when triaging bugs.
#Hosted OAuth servers (Supabase, GitHub MCP, etc.)
- Supabase’s hosted MCP server rejects the standard
mcp:toolsscope and only accepts Supabase-specific scopes (projects:read,database:write, ...). Because they do not expose OAuth discovery metadata or scope negotiation, mcporter cannot auto-register or complete the flow. Workarounds: - Use Supabase’s supported clients (Cursor, Windsurf).
- Self-host their MCP server and configure PAT headers / custom OAuth.
- Ask Supabase to accept the MCP scope or publish their scope list.
- GitHub’s MCP endpoint (
https://api.githubcopilot.com/mcp/) returns “does not support dynamic client registration” when mcporter attempts to connect. Copilot’s backend expects pre-registered client credentials. ConfigureoauthClientId/oauthClientSecretEnvonly if the provider gives you a usable OAuth app; otherwise use their supported client or token/header workaround. - Some hosted servers reject dynamic client registration before returning any authorization URL. mcporter now fails those flows immediately instead of waiting for a browser callback that cannot arrive. If the provider supports a pre-registered OAuth app, configure
oauthClientId,oauthClientSecretEnv, and the requiredoauthTokenEndpointAuthMethod; otherwise use the provider's supported client or token/header workaround.
#Output schemas missing/buggy on many servers
- The MCP spec allows servers to omit
outputSchema. In practice, many hosted MCPs return empty or inconsistent schemas, so features that rely on return types (TypeScript signatures, generated CLIs,createServerProxyreturn helpers) may degrade tounknown. - Workarounds: inspect the server’s README / manual docs for output details, or wrap the tool via
createServerProxyand handle the raw envelope manually. - Potential improvement: allow user-provided schema overrides (e.g.,
mcporter config patch, CLI flag to load schema JSON) so we can fill gaps on a per-tool basis.
#MCP SDK 1.22.0 inline-stdio regression
- Upgrading
@modelcontextprotocol/sdkto 1.22.0 causesmcporter generate-cli --compile(and direct runtimelistTools) to fail against inline STDIO servers withMCP error -32603: Cannot read properties of undefined (reading 'typeName'). - Repro:
pnpm mcporter generate-cli "node mock-stdio.mjs" --compile /tmp/inline-cli --runtime bunusing the inline stdio harness intests/cli-generate-cli.integration.test.ts. - Status: reproduced locally; pinned the SDK to
~1.21.2until upstream ships a fix.
#Next Steps
- Implement true scope negotiation (read discovery metadata, allow
--oauth-scope). - Keep lobbying providers for spec-compliant OAuth behavior.
- Consider adding schema override hooks or auto-caching schema snapshots per tool.
If you run into other recurring pain points, append them here so we can prioritize fixes.