API Error: Tool input_schema uses unsupported oneOf/allOf/anyOf at top level (ClickUp MCP)

API Error: Tool input_schema uses unsupported oneOf/allOf/anyOf at top level (ClickUp MCP)

TL;DR: Upgrade the ClickUp MCP server to a version where the schemas are flattened; the top-level anyOf in getworkspacetasks blocks all 54 tools. The Anthropic API rejects the whole tool registration when one schema is invalid, so a single bad tool hides everything. As a workaround, you cannot fix this client-side; the server schemas must change.

The error

API Error: Tool input_schema uses unsupported oneOf/allOf/anyOf at top level

Fix it

1. Check your installed @taazkareem/clickup-mcp-server version.

Expected: It is 0.12.8 or 0.12.9.

1. Upgrade to the latest release.

Expected: The install completes.

1. Restart Claude Code and check the tool list.

Expected: All 54 ClickUp tools appear.

When this applies

No ClickUp MCP tools load at all in Claude Code and the error names unsupported oneOf/allOf/anyOf at the top level.

When this does NOT apply

If some tools load, the schemas are fine; check the token. Token errors say unauthorized, not schema errors.

Tool compatibility

taazkareem/clickup-mcp-server 0.12.x, Claude Code

Also seen as

• ClickUp MCP no tools loading
• input_schema oneOf ClickUp
• getworkspacetasks anyOf blocks tools

Why it happens

The Anthropic API validates every tool schema on registration and rejects composition keywords at the schema root. getworkspacetasks had a root anyOf, so the entire 54-tool registration failed and the client showed nothing.

Edge cases

• Property-level oneOf (like priority) may also trip strict clients; the flatten fix covers those too.
• Pin the fixed version in your config so a fresh npx does not regress.
• Other MCP clients are more lenient, which is why this shows up mainly in Claude Code.