docs(cli): add comprehensive error documentation

Code quality improvements based on architect/security review:

- Replace .expect() with .ok_or_else() in common.rs:183
  (prevents panic from user input, returns proper error)
- Add # Errors sections to server.rs::run()
- Add # Errors sections to formatters.rs functions (4 functions)
- Remove #![allow(clippy::missing_errors_doc)] suppression
- Update build_server_config docs (remove Panics, expand Errors)

Security audit found only 1 production .expect() - now fixed.
All 502 tests pass.

Author: bug-ops

crates/mcp-cli/src/commands/common.rs

@@ -108,12 +108,9 @@ pub fn load_server_from_config(name: &str) -> Result<(ServerId, ServerConfig)> {
 ///
 /// # Errors
 ///
-/// Returns an error if environment variables or headers are not in KEY=VALUE format.
-///
-/// # Panics
-///
-/// Panics if `server` is `None` when using stdio transport (i.e., when neither
-/// `http` nor `sse` is provided). This is enforced by CLI argument validation.
+/// Returns an error if:
+/// - Environment variables or headers are not in KEY=VALUE format
+/// - `server` is `None` when using stdio transport (neither `http` nor `sse` provided)
 ///
 /// # Examples
 ///
@@ -180,7 +177,8 @@ pub fn build_server_config(
         (id, builder.build())
     } else {
         // Stdio transport (default)
-        let command = server.expect("server is required for stdio transport");
+        let command = server
+            .ok_or_else(|| anyhow::anyhow!("server command is required for stdio transport"))?;
         let id = ServerId::new(&command);
         let mut builder: ServerConfigBuilder = ServerConfig::builder().command(command);
 

crates/mcp-cli/src/commands/server.rs

@@ -286,7 +286,12 @@ impl ServerManager {
 ///
 /// # Errors
 ///
-/// Returns an error if server operation fails.
+/// Returns an error if:
+/// - Claude Desktop configuration file cannot be found or read
+/// - Configuration file contains invalid JSON
+/// - Requested server is not found in configuration (for Info action)
+/// - Server introspection fails (for Info action)
+/// - Output formatting fails
 ///
 /// # Examples
 ///

crates/mcp-cli/src/formatters.rs

@@ -55,12 +55,20 @@ pub mod json {
     /// Format data as JSON.
     ///
     /// Uses pretty-printing with 2-space indentation.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if serialization fails.
     pub fn format<T: Serialize>(data: &T) -> Result<String> {
         let json = serde_json::to_string_pretty(data)?;
         Ok(json)
     }
 
     /// Format data as compact JSON (no formatting).
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if serialization fails.
     pub fn format_compact<T: Serialize>(data: &T) -> Result<String> {
         let json = serde_json::to_string(data)?;
         Ok(json)
@@ -75,6 +83,10 @@ pub mod text {
     ///
     /// Uses JSON representation but without colors or fancy formatting.
     /// Suitable for piping to other commands or scripts.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if serialization fails.
     pub fn format<T: Serialize>(data: &T) -> Result<String> {
         // For text mode, use JSON without pretty printing
         json::format_compact(data)
@@ -88,6 +100,10 @@ pub mod pretty {
     /// Format data as colorized, human-readable output.
     ///
     /// Uses colors and formatting for better terminal readability.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if serialization fails.
     pub fn format<T: Serialize>(data: &T) -> Result<String> {
         // Convert to JSON value first for inspection
         let value = serde_json::to_value(data)?;

crates/mcp-cli/src/main.rs

@@ -5,8 +5,7 @@
 #![allow(clippy::unused_async)]
 #![allow(clippy::cast_possible_truncation)]
 // u128->u64 for millis is safe in practice
-// TODO(phase-7.3): Add comprehensive error documentation to all public CLI functions
-#![allow(clippy::missing_errors_doc)]
+// Error documentation added to all public CLI functions
 #![allow(clippy::needless_collect)]
 #![allow(clippy::unnecessary_wraps)] // API design requires Result for consistency across commands
 #![allow(clippy::unnecessary_literal_unwrap)]