Chroma MCP: Chroma Cloud auth failed (set tenant, database and API key)

TL;DR: Chroma Cloud is a different client mode with different credentials. Set CHROMA_CLIENT_TYPE=cloud plus CHROMA_TENANT, CHROMA_DATABASE and CHROMA_API_KEY. A local host/port config will never authenticate against Cloud.

Authentication failed / unauthorized (Chroma Cloud)

Fix it

1. In the Chroma Cloud dashboard, note your tenant, database, and create an API key.
2. Configure the MCP server for cloud mode:

{
  "env": {
    "CHROMA_CLIENT_TYPE": "cloud",
    "CHROMA_TENANT": "your-tenant-id",
    "CHROMA_DATABASE": "your-database-name",
    "CHROMA_API_KEY": "your-api-key"
  }
}

Or the equivalent --client-type cloud flags.

3. Restart the MCP client.

   Expected: the server authenticates and collections are visible.

When to use this

• Connecting the MCP server to Chroma Cloud (api.trychroma.com).
• Auth failures with a host/port config pointed at Cloud.

When NOT to use this

• Local or self-hosted ChromaDB. Cloud variables do nothing there; use host/port or persistent mode.
• 404s on collections with working auth. That is a collection-name problem.

Compatibility

• chroma-mcp with cloud client support, chromamcpserver.
• Chroma Cloud.

Why it happens

Chroma Cloud authenticates by tenant plus API key, not by host/port. The MCP server picks its client class from CHROMA_CLIENT_TYPE. A config written for local HTTP mode builds the wrong client entirely, so nothing about the request looks like valid Cloud auth.

Edge cases

• Tenant and database are both required. The API key alone is not enough.
• API keys are per-tenant. A key from one tenant fails on another.
• Embedding function API keys (OpenAI etc.) are separate from the Chroma Cloud API key. You may need both.

The chromamcpserver getting-started guide (djm81/chromamcpserver docs/gettingstarted.md) documents the connection details per mode: for cloud mode, CHROMATENANT, CHROMADATABASE and CHROMAAPIKEY are required. The chroma-mcp README (charliiko/chroma-mcp) documents the same cloud client variables: CHROMATENANT, CHROMADATABASE, CHROMAAPIKEY for the Chroma Cloud client. Local-mode configs (host/port) do not work against Cloud. Sources: https://github.com/djm81/chromamcpserver/blob/HEAD/docs/gettingstarted.md and https://github.com/charliiko/chroma-mcp