diff --git a/docs/embeddings/cli.md b/docs/embeddings/cli.md
index ed96fe6a..5dfa99e7 100644
--- a/docs/embeddings/cli.md
+++ b/docs/embeddings/cli.md
@@ -13,21 +13,24 @@ The `llm embed` command can be used to calculate embedding vectors for a string
 The simplest way to use this command is to pass content to it using the `-c/--content` option, like this:
 
 ```bash
-llm embed -c 'This is some content'
+llm embed -c 'This is some content' -m ada-002
 ```
-The command will return a JSON array of floating point numbers directly to the terminal:
+`-m ada-002` specifies the OpenAI `ada-002` model. You will need to have set an OpenAI API key using `llm keys set openai` for this to work.
 
-```json
-[0.123, 0.456, 0.789...]
+You can install plugins to access other models. The [llm-sentence-transformers](https://github.com/simonw/llm-sentence-transformers) plugin can be used to run models on your own laptop, such as the [MiniLM-L6](https://huggingface.co/sentence-transformers/all-MiniLM-L6-v2) model:
+
+```bash
+llm install llm-sentence-transformers
+llm embed -c 'This is some content' -m sentence-transformers/all-MiniLM-L6-v2
 ```
-By default it uses the {ref}`default embedding model <embeddings-cli-embed-models-default>`.
 
-Use the `-m/--model` option to specify a different model:
+The `llm embed` command returns a JSON array of floating point numbers directly to the terminal:
 
-```bash
-llm -m sentence-transformers/all-MiniLM-L6-v2 \
-  -c 'This is some content'
+```json
+[0.123, 0.456, 0.789...]
 ```
+You can omit the `-m/--model` option if you set a {ref}`default embedding model <embeddings-cli-embed-models-default>`.
+
 See {ref}`embeddings-binary` for options to get back embeddings in formats other than JSON.
 
 (embeddings-collections)=
@@ -37,6 +40,11 @@ Embeddings are much more useful if you store them somewhere, so you can calculat
 
 LLM includes the concept of a "collection" of embeddings. A collection groups together a set of stored embeddings created using the same model, each with a unique ID within that collection.
 
+First, we'll set a default model so we don't have to keep repeating it:
+```bash
+llm embed-models default ada-002
+```
+
 The `llm embed` command can store results directly in a named collection like this:
 
 ```bash
diff --git a/docs/embeddings/python-api.md b/docs/embeddings/python-api.md
index 3f3e6f23..cfe338b7 100644
--- a/docs/embeddings/python-api.md
+++ b/docs/embeddings/python-api.md
@@ -106,6 +106,13 @@ A collection instance has the following properties and methods:
 - `similar_by_vector(vector: List[float], number: int=10, skip_id: str=None)` - returns a list of entries that are most similar to the given embedding vector, optionally skipping the entry with the given ID
 - `delete()` - deletes the collection and its embeddings from the database
 
+There is also a `Collection.exists(db, name)` class method which returns a boolean value and can be used to determine if a collection exists or not in a database:
+
+```python
+if Collection.exists(db, "entries"):
+    print("The entries collection exists")
+```
+
 (embeddings-python-similar)=
 ## Retrieving similar items
 
diff --git a/llm/__init__.py b/llm/__init__.py
index 77756cae..e2ac276d 100644
--- a/llm/__init__.py
+++ b/llm/__init__.py
@@ -115,7 +115,7 @@ def get_embedding_model(name):
     try:
         return aliases[name]
     except KeyError:
-        raise UnknownModelError("Unknown model: " + name)
+        raise UnknownModelError("Unknown model: " + str(name))
 
 
 def get_embedding_model_aliases() -> Dict[str, EmbeddingModel]:
diff --git a/llm/cli.py b/llm/cli.py
index 91c8049d..d985fe84 100644
--- a/llm/cli.py
+++ b/llm/cli.py
@@ -929,20 +929,28 @@ def get_db():
     model_obj = None
     if collection:
         db = get_db()
-        collection_obj = Collection(collection, db, model_id=model)
-        model_obj = collection_obj.model()
+        if Collection.exists(db, collection):
+            # Load existing collection and use its model
+            collection_obj = Collection(collection, db)
+            model_obj = collection_obj.model()
+        else:
+            # We will create a new one, but that means model is required
+            if not model:
+                model = get_default_embedding_model()
+                if model is None:
+                    raise click.ClickException(
+                        "You need to specify a model (no default model is set)"
+                    )
+            collection_obj = Collection(collection, db=db, model_id=model)
+            model_obj = collection_obj.model()
 
     if model_obj is None:
-        if not model:
-            model = get_default_embedding_model()
-            if model is None:
-                raise click.ClickException(
-                    "You need to specify a model (no default model is set)"
-                )
         try:
             model_obj = get_embedding_model(model)
-        except UnknownModelError as ex:
-            raise click.ClickException(str(ex))
+        except UnknownModelError:
+            raise click.ClickException(
+                "You need to specify a model (no default model is set)"
+            )
 
     show_output = True
     if collection and (format_ is None):
diff --git a/llm/embeddings.py b/llm/embeddings.py
index 4ea8d2db..1e128ad5 100644
--- a/llm/embeddings.py
+++ b/llm/embeddings.py
@@ -288,6 +288,17 @@ def similar(self, text: str, number: int = 10) -> List[Entry]:
         comparison_vector = self.model().embed(text)
         return self.similar_by_vector(comparison_vector, number)
 
+    @classmethod
+    def exists(cls, db: Database, name: str) -> bool:
+        """
+        Does this collection exist in the database?
+
+        Args:
+            name (str): Name of the collection
+        """
+        rows = list(db["collections"].rows_where("name = ?", [name]))
+        return bool(rows)
+
     def delete(self):
         """
         Delete the collection and its embeddings from the database
diff --git a/tests/test_embed_cli.py b/tests/test_embed_cli.py
index 71d1006c..7a844c53 100644
--- a/tests/test_embed_cli.py
+++ b/tests/test_embed_cli.py
@@ -102,9 +102,8 @@ def test_embed_store(user_path, metadata, metadata_error):
     assert embeddings_db.exists()
     # Check the contents
     db = sqlite_utils.Database(str(embeddings_db))
-    assert list(db["collections"].rows) == [
-        {"id": 1, "name": "items", "model": "embed-demo"}
-    ]
+    rows = list(db["collections"].rows)
+    assert rows == [{"id": 1, "name": "items", "model": "embed-demo"}]
     expected_metadata = None
     if metadata and not metadata_error:
         expected_metadata = metadata
@@ -390,3 +389,34 @@ def test_default_embedding_model():
     result5 = runner.invoke(cli, ["embed-models", "default"])
     assert result5.exit_code == 0
     assert result5.output == "<No default embedding model set>\n"
+
+
+@pytest.mark.parametrize("default_is_set", (False, True))
+@pytest.mark.parametrize("command", ("embed", "embed-multi"))
+def test_default_embed_model_errors(user_path, default_is_set, command):
+    runner = CliRunner()
+    if default_is_set:
+        (user_path / "default_embedding_model.txt").write_text(
+            "embed-demo", encoding="utf8"
+        )
+    args = []
+    input = None
+    if command == "embed-multi":
+        args = ["embed-multi", "example", "-"]
+        input = "id,name\n1,hello"
+    else:
+        args = ["embed", "example", "1", "-c", "hello world"]
+    result = runner.invoke(cli, args, input=input, catch_exceptions=False)
+    if default_is_set:
+        assert result.exit_code == 0
+    else:
+        assert result.exit_code == 1
+        assert "You need to specify a model (no default model is set)" in result.output
+        # Now set the default model and try again
+        result2 = runner.invoke(cli, ["embed-models", "default", "embed-demo"])
+        assert result2.exit_code == 0
+        result3 = runner.invoke(cli, args, input=input, catch_exceptions=False)
+        assert result3.exit_code == 0
+    # At the end of this, there should be 2 embeddings
+    db = sqlite_utils.Database(str(user_path / "embeddings.db"))
+    assert db["embeddings"].count == 1