diff --git a/Cargo.lock b/Cargo.lock
index 2898374..06e704c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -225,6 +225,7 @@ dependencies = [
  "cairo-coverage-test-utils",
  "camino",
  "clap",
+ "console",
  "snapbox",
  "walkdir",
  "which",
@@ -507,6 +508,19 @@ version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5b63caa9aa9397e2d9480a9b13673856c78d8ac123288526c37d7839f2a86990"
 
+[[package]]
+name = "console"
+version = "0.15.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea3c6ecd8059b57859df5c69830340ed3c41d30e3da0c1cbed90a96ac853041b"
+dependencies = [
+ "encode_unicode",
+ "libc",
+ "once_cell",
+ "unicode-width",
+ "windows-sys",
+]
+
 [[package]]
 name = "const-fnv1a-hash"
 version = "1.1.0"
@@ -724,6 +738,12 @@ dependencies = [
  "log",
 ]
 
+[[package]]
+name = "encode_unicode"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34aa73646ffb006b8f5147f3dc182bd4bcb190227ce861fc4a4844bf8e3cb2c0"
+
 [[package]]
 name = "env_home"
 version = "0.1.0"
@@ -1986,6 +2006,12 @@ version = "1.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f6ccf251212114b54433ec949fd6a7841275f9ada20dddd2f29e9ceea4501493"
 
+[[package]]
+name = "unicode-width"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fc81956842c57dac11422a97c3b8195a1ff727f06e85c84ed2e8aa277c9a0fd"
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.6"
diff --git a/Cargo.toml b/Cargo.toml
index a75eb7e..6b04242 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,15 +11,17 @@ version = "0.4.0"
 edition = "2024"
 
 [workspace.dependencies]
+cairo-lang-sierra = "2.10.1"
+cairo-lang-sierra-to-casm = "2.10.1"
+cairo-lang-starknet-classes = "2.10.1"
+cairo-annotations = "0.2.2"
+
 anyhow = "1.0.96"
 assert_fs = "1.1.2"
 camino = "1.1.9"
 clap = { version = "4.5.30", features = ["derive"] }
 criterion = "0.5"
-cairo-annotations = "0.2.2"
-cairo-lang-sierra = "2.10.1"
-cairo-lang-sierra-to-casm = "2.10.1"
-cairo-lang-starknet-classes = "2.10.1"
+console = "0.15.10"
 itertools = "0.14.0"
 ignore = "0.4.23"
 serde = "1.0.218"
diff --git a/crates/cairo-coverage/Cargo.toml b/crates/cairo-coverage/Cargo.toml
index fc5b454..ad8057b 100644
--- a/crates/cairo-coverage/Cargo.toml
+++ b/crates/cairo-coverage/Cargo.toml
@@ -5,6 +5,7 @@ edition.workspace = true
 
 [dependencies]
 cairo-coverage-core = { path = "../cairo-coverage-core" }
+console.workspace = true
 camino.workspace = true
 anyhow.workspace = true
 clap.workspace = true
diff --git a/crates/cairo-coverage/src/args/run.rs b/crates/cairo-coverage/src/args/run.rs
index af3999c..fd01732 100644
--- a/crates/cairo-coverage/src/args/run.rs
+++ b/crates/cairo-coverage/src/args/run.rs
@@ -34,11 +34,11 @@ pub enum IncludedComponent {
 fn parse_trace_file(path: &str) -> Result<Utf8PathBuf> {
     let trace_file = Utf8PathBuf::from(path);
 
-    ensure!(trace_file.exists(), "Trace file does not exist");
-    ensure!(trace_file.is_file(), "Trace file is not a file");
+    ensure!(trace_file.exists(), "trace file does not exist");
+    ensure!(trace_file.is_file(), "trace file is not a file");
     ensure!(
         matches!(trace_file.extension(), Some("json")),
-        "Trace file must have a JSON extension"
+        "trace file must have a JSON extension"
     );
 
     Ok(trace_file)
@@ -47,8 +47,8 @@ fn parse_trace_file(path: &str) -> Result<Utf8PathBuf> {
 fn parse_project_path(path: &str) -> Result<Utf8PathBuf> {
     let project_path = Utf8PathBuf::from(path);
 
-    ensure!(project_path.exists(), "Project path does not exist");
-    ensure!(project_path.is_dir(), "Project path is not a directory");
+    ensure!(project_path.exists(), "project path does not exist");
+    ensure!(project_path.is_dir(), "project path is not a directory");
 
     Ok(project_path)
 }
diff --git a/crates/cairo-coverage/src/commands/clean.rs b/crates/cairo-coverage/src/commands/clean.rs
index d8ea192..c65b2b4 100644
--- a/crates/cairo-coverage/src/commands/clean.rs
+++ b/crates/cairo-coverage/src/commands/clean.rs
@@ -1,4 +1,5 @@
 use crate::args::clean::CleanArgs;
+use crate::ui;
 use anyhow::{Context, Result};
 use std::fs;
 use walkdir::WalkDir;
@@ -13,7 +14,7 @@ pub fn run(
 ) -> Result<()> {
     let target_file_name = files_to_delete
         .file_name()
-        .context("Failed to obtain the file name from `files_to_delete`.")?;
+        .context("failed to obtain the file name from `--files-to-delete`")?;
 
     WalkDir::new(root_dir)
         .into_iter()
@@ -24,16 +25,17 @@ pub fn run(
 
             if let Some(file_name) = path.file_name() {
                 if file_name == target_file_name {
-                    println!("Deleting file: {}", path.display());
+                    let path_display = path.display();
+                    ui::msg(format!("deleting file: {path_display}"));
                     fs::remove_file(path)
-                        .with_context(|| format!("Failed to delete file: {}", path.display()))?;
+                        .with_context(|| format!("failed to delete file: {path_display}"))?;
                 }
             }
 
             Ok(())
         })?;
 
-    println!("Cleanup complete.");
+    ui::msg("cleanup complete");
     Ok(())
 }
 
diff --git a/crates/cairo-coverage/src/commands/run.rs b/crates/cairo-coverage/src/commands/run.rs
index 1246c34..34f0640 100644
--- a/crates/cairo-coverage/src/commands/run.rs
+++ b/crates/cairo-coverage/src/commands/run.rs
@@ -25,9 +25,9 @@ pub fn run(
         .append(true)
         .create(true)
         .open(&output_path)
-        .context(format!("Failed to open output file at path: {output_path}"))?
+        .context(format!("failed to open output file at path: {output_path}"))?
         .write_all(lcov.as_bytes())
-        .context("Failed to write to output file")?;
+        .context("failed to write to output file")?;
 
     Ok(())
 }
diff --git a/crates/cairo-coverage/src/main.rs b/crates/cairo-coverage/src/main.rs
index 2b2894f..9e07d2f 100644
--- a/crates/cairo-coverage/src/main.rs
+++ b/crates/cairo-coverage/src/main.rs
@@ -1,21 +1,36 @@
 use crate::args::{CairoCoverageArgs, Command};
 use anyhow::Result;
+
 use clap::Parser;
+use std::process::ExitCode;
 
 mod args;
 mod commands;
+mod ui;
+
+fn main() -> ExitCode {
+    if let Err(error) = main_inner() {
+        ui::error(error);
+        ExitCode::FAILURE
+    } else {
+        ExitCode::SUCCESS
+    }
+}
 
-fn main() -> Result<()> {
+fn main_inner() -> Result<()> {
     let cairo_coverage_args = CairoCoverageArgs::parse();
 
-    let command = match cairo_coverage_args.command {
-        Some(command) => command,
-        // TODO:
-        // * In 0.5.0 add deprecation warning
-        // * In 0.6.0 remove the default command
-        None => Command::Run(cairo_coverage_args.run_args.unwrap_or_else(|| {
+    // TODO:
+    // * In 0.6.0 remove the default command
+    let command = if let Some(command) = cairo_coverage_args.command {
+        command
+    } else {
+        ui::warning("running `cairo-coverage` without a subcommand is deprecated");
+        ui::help("consider using `cairo-coverage run`");
+
+        Command::Run(cairo_coverage_args.run_args.unwrap_or_else(|| {
             unreachable!("`run_args` should be set when no subcommand is provided")
-        })),
+        }))
     };
 
     commands::run(command)
diff --git a/crates/cairo-coverage/src/ui.rs b/crates/cairo-coverage/src/ui.rs
new file mode 100644
index 0000000..a9e157f
--- /dev/null
+++ b/crates/cairo-coverage/src/ui.rs
@@ -0,0 +1,28 @@
+//! UI utilities for the Cairo coverage tool.
+//! All human-oriented messaging must use this module to communicate with the user.
+//! Messages should be lowercased and should not end with a period.
+use console::style;
+use std::fmt::Display;
+
+/// Print a warning message.
+pub fn warning(message: impl Display) {
+    let tag = style("warning").yellow();
+    println!("{tag}: {message}");
+}
+
+/// Print an error message.
+pub fn error(message: impl Display) {
+    let tag = style("error").red();
+    println!("{tag}: {message}");
+}
+
+/// Print a help message.
+pub fn help(message: impl Display) {
+    let tag = style("help").bold();
+    println!("{tag}: {message}");
+}
+
+/// Print a message.
+pub fn msg(message: impl Display) {
+    println!("{message}");
+}