TL;DR: ChromaDB is up; the collection name is wrong. List the collections that exist, fix the name, retry.

```text
Collection [my_docs] does not exist
```

## Fix it

1. List the collections. Use the MCP server's list-collections tool, or:

```bash
curl http://YOUR_CHROMA_HOST:8000/api/v2/collections
```

   Expected: JSON with the real collection names.

2. Fix the name in your tool call. Common mistakes: pluralization, dashes vs underscores, case.

3. If the collection should exist but does not, create it first with the create-collection tool, or check you are pointed at the right ChromaDB (dev vs prod data dirs get mixed up).

   Expected: queries run against the collection.

## When to use this

- ChromaDB connects fine, but a specific collection is reported missing.
- The name was typed by hand or generated by the agent.

## When NOT to use this

- Connection refused. ChromaDB is down.
- No collections exist at all. Create one first.

## Compatibility

- chroma-mcp, rkilchmn/chroma-mcp-server.
- ChromaDB local and server modes.

## Why it happens

Collection names are exact strings with no fuzzy matching. In persistent mode, each data directory is its own universe of collections, so pointing at a fresh or different directory looks exactly like a missing collection.

## Edge cases

- Persistent mode: the data directory determines which collections exist. A new `--path` means zero collections.
- Collection names cannot be renamed. Create the correctly named one and migrate data.
- Some servers auto-create configured collections at startup. If yours does not, create them explicitly.