diff --git a/pkg/cmd/chat.go b/pkg/cmd/chat.go
index 527529d..be93369 100644
--- a/pkg/cmd/chat.go
+++ b/pkg/cmd/chat.go
@@ -15,6 +15,10 @@ func ChatCmd(ctx *lmcli.Context) *cobra.Command {
 		Short: "Open the chat interface",
 		Long:  `Open the chat interface, optionally on a given conversation.`,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			err := validateGenerationFlags(ctx, cmd)
+			if err != nil {
+				return err
+			}
 			shortname := ""
 			if len(args) == 1 {
 				shortname = args[0]
@@ -25,7 +29,7 @@ func ChatCmd(ctx *lmcli.Context) *cobra.Command {
 					return err
 				}
 			}
-			err := tui.Launch(ctx, shortname)
+			err = tui.Launch(ctx, shortname)
 			if err != nil {
 				return fmt.Errorf("Error fetching LLM response: %v", err)
 			}
@@ -39,6 +43,6 @@ func ChatCmd(ctx *lmcli.Context) *cobra.Command {
 			return ctx.Store.ConversationShortNameCompletions(toComplete), compMode
 		},
 	}
-	applyPromptFlags(ctx, cmd)
+	applyGenerationFlags(ctx, cmd)
 	return cmd
 }
diff --git a/pkg/cmd/cmd.go b/pkg/cmd/cmd.go
index 593fff2..764cea0 100644
--- a/pkg/cmd/cmd.go
+++ b/pkg/cmd/cmd.go
@@ -1,6 +1,8 @@
 package cmd
 
 import (
+	"fmt"
+	"slices"
 	"strings"
 
 	"git.mlow.ca/mlow/lmcli/pkg/lmcli"
@@ -37,27 +39,43 @@ func RootCmd(ctx *lmcli.Context) *cobra.Command {
 	return root
 }
 
-func applyPromptFlags(ctx *lmcli.Context, cmd *cobra.Command) {
+func applyGenerationFlags(ctx *lmcli.Context, cmd *cobra.Command) {
 	f := cmd.Flags()
 
+	// -m, --model
 	f.StringVarP(
-		ctx.Config.Defaults.Model,
-		"model", "m",
-		*ctx.Config.Defaults.Model,
-		"The model to generate a response with",
+		ctx.Config.Defaults.Model, "model", "m",
+		*ctx.Config.Defaults.Model, "Which model to generate a response with",
 	)
 	cmd.RegisterFlagCompletionFunc("model", func(*cobra.Command, []string, string) ([]string, cobra.ShellCompDirective) {
 		return ctx.GetModels(), cobra.ShellCompDirectiveDefault
 	})
 
+	// --max-length
 	f.IntVar(ctx.Config.Defaults.MaxTokens, "max-length", *ctx.Config.Defaults.MaxTokens, "Maximum response tokens")
+	// --temperature
 	f.Float32VarP(ctx.Config.Defaults.Temperature, "temperature", "t", *ctx.Config.Defaults.Temperature, "Sampling temperature")
 
+	// --system-prompt
 	f.StringVar(ctx.Config.Defaults.SystemPrompt, "system-prompt", *ctx.Config.Defaults.SystemPrompt, "System prompt")
-	f.StringVar(&ctx.SystemPromptFile, "system-prompt-file", "", "A path to a file containing the system prompt")
+	// --system-prompt-file
+	f.StringVar(&ctx.Config.Defaults.SystemPromptFile, "system-prompt-file", ctx.Config.Defaults.SystemPromptFile, "A path to a file containing the system prompt")
 	cmd.MarkFlagsMutuallyExclusive("system-prompt", "system-prompt-file")
 }
 
+func validateGenerationFlags(ctx *lmcli.Context, cmd *cobra.Command) error {
+	f := cmd.Flags()
+
+	model, err := f.GetString("model")
+	if err != nil {
+		return fmt.Errorf("Error parsing --model: %w", err)
+	}
+	if !slices.Contains(ctx.GetModels(), model) {
+		return fmt.Errorf("Unknown model: %s", model)
+	}
+	return nil
+}
+
 // inputFromArgsOrEditor returns either the provided input from the args slice
 // (joined with spaces), or if len(args) is 0, opens an editor and returns
 // whatever input was provided there. placeholder is a string which populates
diff --git a/pkg/cmd/continue.go b/pkg/cmd/continue.go
index 73503d0..965efd1 100644
--- a/pkg/cmd/continue.go
+++ b/pkg/cmd/continue.go
@@ -23,6 +23,11 @@ func ContinueCmd(ctx *lmcli.Context) *cobra.Command {
 			return nil
 		},
 		RunE: func(cmd *cobra.Command, args []string) error {
+			err := validateGenerationFlags(ctx, cmd)
+			if err != nil {
+				return err
+			}
+
 			shortName := args[0]
 			conversation := cmdutil.LookupConversation(ctx, shortName)
 
@@ -68,6 +73,6 @@ func ContinueCmd(ctx *lmcli.Context) *cobra.Command {
 			return ctx.Store.ConversationShortNameCompletions(toComplete), compMode
 		},
 	}
-	applyPromptFlags(ctx, cmd)
+	applyGenerationFlags(ctx, cmd)
 	return cmd
 }
diff --git a/pkg/cmd/new.go b/pkg/cmd/new.go
index aca7a9e..45a2002 100644
--- a/pkg/cmd/new.go
+++ b/pkg/cmd/new.go
@@ -15,6 +15,11 @@ func NewCmd(ctx *lmcli.Context) *cobra.Command {
 		Short: "Start a new conversation",
 		Long:  `Start a new conversation with the Large Language Model.`,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			err := validateGenerationFlags(ctx, cmd)
+			if err != nil {
+				return err
+			}
+
 			input := inputFromArgsOrEditor(args, "# Start a new conversation below\n", "")
 			if input == "" {
 				return fmt.Errorf("No message was provided.")
@@ -22,8 +27,7 @@ func NewCmd(ctx *lmcli.Context) *cobra.Command {
 
 			var messages []api.Message
 
-			// TODO: probably just make this part of the conversation
-			system := ctx.GetSystemPrompt()
+			system := ctx.Config.GetSystemPrompt()
 			if system != "" {
 				messages = append(messages, api.Message{
 					Role:    api.MessageRoleSystem,
@@ -57,6 +61,6 @@ func NewCmd(ctx *lmcli.Context) *cobra.Command {
 		},
 	}
 
-	applyPromptFlags(ctx, cmd)
+	applyGenerationFlags(ctx, cmd)
 	return cmd
 }
diff --git a/pkg/cmd/prompt.go b/pkg/cmd/prompt.go
index 8664c91..9d17959 100644
--- a/pkg/cmd/prompt.go
+++ b/pkg/cmd/prompt.go
@@ -15,6 +15,11 @@ func PromptCmd(ctx *lmcli.Context) *cobra.Command {
 		Short: "Do a one-shot prompt",
 		Long:  `Prompt the Large Language Model and get a response.`,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			err := validateGenerationFlags(ctx, cmd)
+			if err != nil {
+				return err
+			}
+
 			input := inputFromArgsOrEditor(args, "# Write your prompt below\n", "")
 			if input == "" {
 				return fmt.Errorf("No message was provided.")
@@ -22,8 +27,7 @@ func PromptCmd(ctx *lmcli.Context) *cobra.Command {
 
 			var messages []api.Message
 
-			// TODO: stop supplying system prompt as a message
-			system := ctx.GetSystemPrompt()
+			system := ctx.Config.GetSystemPrompt()
 			if system != "" {
 				messages = append(messages, api.Message{
 					Role:    api.MessageRoleSystem,
@@ -36,7 +40,7 @@ func PromptCmd(ctx *lmcli.Context) *cobra.Command {
 				Content: input,
 			})
 
-			_, err := cmdutil.Prompt(ctx, messages, nil)
+			_, err = cmdutil.Prompt(ctx, messages, nil)
 			if err != nil {
 				return fmt.Errorf("Error fetching LLM response: %v", err)
 			}
@@ -44,6 +48,6 @@ func PromptCmd(ctx *lmcli.Context) *cobra.Command {
 		},
 	}
 
-	applyPromptFlags(ctx, cmd)
+	applyGenerationFlags(ctx, cmd)
 	return cmd
 }
diff --git a/pkg/cmd/reply.go b/pkg/cmd/reply.go
index 6338566..a0c0a65 100644
--- a/pkg/cmd/reply.go
+++ b/pkg/cmd/reply.go
@@ -22,6 +22,11 @@ func ReplyCmd(ctx *lmcli.Context) *cobra.Command {
 			return nil
 		},
 		RunE: func(cmd *cobra.Command, args []string) error {
+			err := validateGenerationFlags(ctx, cmd)
+			if err != nil {
+				return err
+			}
+
 			shortName := args[0]
 			conversation := cmdutil.LookupConversation(ctx, shortName)
 
@@ -45,6 +50,6 @@ func ReplyCmd(ctx *lmcli.Context) *cobra.Command {
 		},
 	}
 
-	applyPromptFlags(ctx, cmd)
+	applyGenerationFlags(ctx, cmd)
 	return cmd
 }
diff --git a/pkg/cmd/retry.go b/pkg/cmd/retry.go
index d88dd87..e2ba866 100644
--- a/pkg/cmd/retry.go
+++ b/pkg/cmd/retry.go
@@ -22,6 +22,11 @@ func RetryCmd(ctx *lmcli.Context) *cobra.Command {
 			return nil
 		},
 		RunE: func(cmd *cobra.Command, args []string) error {
+			err := validateGenerationFlags(ctx, cmd)
+			if err != nil {
+				return err
+			}
+
 			shortName := args[0]
 			conversation := cmdutil.LookupConversation(ctx, shortName)
 
@@ -68,6 +73,6 @@ func RetryCmd(ctx *lmcli.Context) *cobra.Command {
 
 	cmd.Flags().Int("offset", 0, "Offset from the last message to retry from.")
 
-	applyPromptFlags(ctx, cmd)
+	applyGenerationFlags(ctx, cmd)
 	return cmd
 }
diff --git a/pkg/lmcli/config.go b/pkg/lmcli/config.go
index d266379..89190e1 100644
--- a/pkg/lmcli/config.go
+++ b/pkg/lmcli/config.go
@@ -10,10 +10,11 @@ import (
 
 type Config struct {
 	Defaults *struct {
-		SystemPrompt *string  `yaml:"systemPrompt" default:"You are a helpful assistant."`
-		MaxTokens    *int     `yaml:"maxTokens" default:"256"`
-		Temperature  *float32 `yaml:"temperature" default:"0.7"`
-		Model        *string  `yaml:"model" default:"gpt-4"`
+		SystemPromptFile string   `yaml:"systemPromptFile,omitempty"`
+		SystemPrompt     *string  `yaml:"systemPrompt" default:"You are a helpful assistant."`
+		MaxTokens        *int     `yaml:"maxTokens" default:"256"`
+		Temperature      *float32 `yaml:"temperature" default:"0.2"`
+		Model            *string  `yaml:"model" default:"gpt-4"`
 	} `yaml:"defaults"`
 	Conversations *struct {
 		TitleGenerationModel *string `yaml:"titleGenerationModel" default:"gpt-3.5-turbo"`
@@ -22,10 +23,10 @@ type Config struct {
 		EnabledTools []string `yaml:"enabledTools"`
 	} `yaml:"tools"`
 	Providers []*struct {
-		Name    *string   `yaml:"name"`
+		Name    *string   `yaml:"name,omitempty"`
 		Kind    *string   `yaml:"kind"`
-		BaseURL *string   `yaml:"baseUrl"`
-		APIKey  *string   `yaml:"apiKey"`
+		BaseURL *string   `yaml:"baseUrl,omitempty"`
+		APIKey  *string   `yaml:"apiKey,omitempty"`
 		Models  *[]string `yaml:"models"`
 	} `yaml:"providers"`
 	Chroma *struct {
@@ -68,3 +69,17 @@ func NewConfig(configFile string) (*Config, error) {
 
 	return c, nil
 }
+
+func (c *Config) GetSystemPrompt() string {
+	if c.Defaults.SystemPromptFile != "" {
+		content, err := util.ReadFileContents(c.Defaults.SystemPromptFile)
+		if err != nil {
+			Fatal("Could not read file contents at %s: %v\n", c.Defaults.SystemPromptFile, err)
+		}
+		return content
+	}
+	if c.Defaults.SystemPrompt == nil {
+		return ""
+	}
+	return *c.Defaults.SystemPrompt
+}
diff --git a/pkg/lmcli/lmcli.go b/pkg/lmcli/lmcli.go
index 651088f..3ee8c3e 100644
--- a/pkg/lmcli/lmcli.go
+++ b/pkg/lmcli/lmcli.go
@@ -12,7 +12,6 @@ import (
 	"git.mlow.ca/mlow/lmcli/pkg/api/provider/google"
 	"git.mlow.ca/mlow/lmcli/pkg/api/provider/ollama"
 	"git.mlow.ca/mlow/lmcli/pkg/api/provider/openai"
-	"git.mlow.ca/mlow/lmcli/pkg/util"
 	"git.mlow.ca/mlow/lmcli/pkg/util/tty"
 	"gorm.io/driver/sqlite"
 	"gorm.io/gorm"
@@ -24,8 +23,6 @@ type Context struct {
 
 	Chroma       *tty.ChromaHighlighter
 	EnabledTools []api.ToolSpec
-
-	SystemPromptFile string
 }
 
 func NewContext() (*Context, error) {
@@ -57,7 +54,7 @@ func NewContext() (*Context, error) {
 		}
 	}
 
-	return &Context{config, store, chroma, enabledTools, ""}, nil
+	return &Context{config, store, chroma, enabledTools}, nil
 }
 
 func (c *Context) GetModels() (models []string) {
@@ -139,17 +136,6 @@ func (c *Context) GetModelProvider(model string) (string, api.ChatCompletionProv
 	return "", nil, fmt.Errorf("unknown model: %s", model)
 }
 
-func (c *Context) GetSystemPrompt() string {
-	if c.SystemPromptFile != "" {
-		content, err := util.ReadFileContents(c.SystemPromptFile)
-		if err != nil {
-			Fatal("Could not read file contents at %s: %v\n", c.SystemPromptFile, err)
-		}
-		return content
-	}
-	return *c.Config.Defaults.SystemPrompt
-}
-
 func configDir() string {
 	var configDir string
 
diff --git a/pkg/tui/views/chat/chat.go b/pkg/tui/views/chat/chat.go
index cdd5223..9984448 100644
--- a/pkg/tui/views/chat/chat.go
+++ b/pkg/tui/views/chat/chat.go
@@ -143,7 +143,7 @@ func Chat(shared shared.Shared) Model {
 	m.replyCursor.SetChar(" ")
 	m.replyCursor.Focus()
 
-	system := shared.Ctx.GetSystemPrompt()
+	system := shared.Ctx.Config.GetSystemPrompt()
 	if system != "" {
 		m.messages = []api.Message{{
 			Role:    api.MessageRoleSystem,
diff --git a/pkg/util/util.go b/pkg/util/util.go
index 8673aef..91b4feb 100644
--- a/pkg/util/util.go
+++ b/pkg/util/util.go
@@ -21,7 +21,7 @@ func InputFromEditor(placeholder string, pattern string, content string) (string
 	msgFile, _ := os.CreateTemp("/tmp", pattern)
 	defer os.Remove(msgFile.Name())
 
-	os.WriteFile(msgFile.Name(), []byte(placeholder + content), os.ModeAppend)
+	os.WriteFile(msgFile.Name(), []byte(placeholder+content), os.ModeAppend)
 
 	editor := os.Getenv("EDITOR")
 	if editor == "" {
@@ -137,8 +137,8 @@ func SetStructDefaults(data interface{}) bool {
 		}
 
 		// Get the "default" struct tag
-		defaultTag := v.Type().Field(i).Tag.Get("default")
-		if defaultTag == "" {
+		defaultTag, ok := v.Type().Field(i).Tag.Lookup("default")
+		if (!ok) {
 			continue
 		}