# 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 get_workspace_tasks 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.
2. Upgrade to the latest release.
   Expected: The install completes.
3. 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
- get_workspace_tasks anyOf blocks tools

## Why it happens

The Anthropic API validates every tool schema on registration and rejects composition keywords at the schema root. get_workspace_tasks 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.