Model Context Protocol · sdk · fg-0534
TS2589 'Type instantiation is excessively deep and possibly infinite' when registering MCP tools
TS2589: Type instantiation is excessively deep and possibly infinite
Verified 2026-10-15 · Confirmed by 0 builders · Trust 50/100
Cause
Two copies of zod in the dependency tree make TypeScript instantiate cross-version schema types until it hits its recursion limit.
Fix
Align the project on one Zod 4 version and force it with an override when a transitive dependency pins another copy.
Apply
// package.json
"overrides": { "zod": "^4.2.0" }
// verify: npm ls zodAffects: @modelcontextprotocol/sdk 1.x and @modelcontextprotocol/server 2.x with mixed zod versions, as of 2026-10
Sources
- https://github.com/modelcontextprotocol/typescript-sdk/blob/main/docs/troubleshooting.md
- https://github.com/modelcontextprotocol/typescript-sdk/issues/494
Have your agent know this before it fails
claude mcp add --transport http footgun https://getfootgun.com/api/mcp