fix(cli): add detailed --help documentation for agent create command

Fixes bounty issue #1396

The 'cortex agent create --help' command previously only displayed
'Create a new agent interactively' without explaining what fields
the interactive wizard would ask for. This commit adds:

- Comprehensive long_about text documenting required vs optional fields
- after_help with usage examples
- Enhanced doc comments on CreateArgs fields explaining their purpose
- Value names for better help output clarity

Author: factorydroid

cortex-cli/src/agent_cmd.rs

@@ -29,6 +29,35 @@ pub enum AgentSubcommand {
     Show(ShowArgs),
 
     /// Create a new agent interactively.
+    #[command(
+        long_about = "Create a new agent interactively.\n\n\
+            This command launches an interactive wizard that guides you through creating \
+            a custom agent. You can also use command-line flags to pre-fill values or \
+            skip the interactive prompts entirely with --non-interactive.\n\n\
+            REQUIRED FIELDS:\n  \
+            - name: Unique identifier for the agent (alphanumeric, hyphens, underscores)\n\n\
+            OPTIONAL FIELDS (prompted in interactive mode):\n  \
+            - description: What this agent does\n  \
+            - mode: primary (user-facing), subagent (invoked by others), or all (both)\n  \
+            - system_prompt: Instructions that define the agent's behavior\n  \
+            - allowed_tools: Which tools the agent can use (default: all)\n  \
+            - denied_tools: Which tools the agent cannot use\n  \
+            - temperature: Creativity level 0.0-2.0 (lower = more focused)\n  \
+            - model: Override the default language model\n  \
+            - color: Hex color code for UI display (e.g., #22c55e)",
+        after_help = "EXAMPLES:\n    \
+            # Interactive mode (recommended for first-time users)\n    \
+            cortex agent create\n\n    \
+            # Create with name pre-filled\n    \
+            cortex agent create --name my-helper\n\n    \
+            # Non-interactive with minimal required fields\n    \
+            cortex agent create --name my-agent --non-interactive\n\n    \
+            # AI-generated agent from description\n    \
+            cortex agent create --generate \"A Rust expert focused on memory safety\"\n\n\
+            AGENT FILE LOCATION:\n    \
+            Agents are saved to ~/.fabric/agents/<name>.md\n\n\
+            For more information, see: cortex agent show <name>"
+    )]
     Create(CreateArgs),
 
     /// Remove a user-defined agent.
@@ -69,28 +98,42 @@ pub struct ShowArgs {
 /// Arguments for create command.
 #[derive(Debug, Parser)]
 pub struct CreateArgs {
-    /// Agent name (if not provided, interactive mode will prompt).
+    /// Agent name [REQUIRED in non-interactive mode].
+    ///
+    /// Unique identifier for the agent. Must contain only alphanumeric
+    /// characters, hyphens, and underscores. If not provided, interactive
+    /// mode will prompt for it.
     #[arg(short, long)]
     pub name: Option<String>,
 
-    /// Agent description.
+    /// Brief description of what this agent does.
+    ///
+    /// Used in agent listings and help text. Defaults to "Custom agent: <name>".
     #[arg(short, long)]
     pub description: Option<String>,
 
     /// Agent mode: primary, subagent, or all.
-    #[arg(short, long)]
+    ///
+    /// - primary: User-facing agent, appears in main agent selection
+    /// - subagent: Can only be invoked by other agents
+    /// - all: Available as both primary and subagent
+    #[arg(short, long, value_name = "MODE")]
     pub mode: Option<String>,
 
-    /// Skip interactive prompts and use defaults.
+    /// Skip interactive prompts and use defaults for optional fields.
+    ///
+    /// Requires --name to be specified. Uses default values for description,
+    /// mode (primary), and system prompt.
     #[arg(long)]
     pub non_interactive: bool,
 
     /// Generate agent using AI from a natural language description.
+    ///
     /// Example: --generate "A Rust expert that helps with memory safety and performance"
     #[arg(short, long, value_name = "DESCRIPTION")]
     pub generate: Option<String>,
 
-    /// Model to use for AI generation (default: gpt-4o).
+    /// Model to use for AI generation.
     #[arg(long, default_value = "gpt-4o")]
     pub model: String,
 }