diff --git a/src/tools/bash.rs b/src/tools/bash.rs
new file mode 100644
index 0000000..d2c1e85
--- /dev/null
+++ b/src/tools/bash.rs
@@ -0,0 +1,315 @@
+use std::path::Path;
+use std::process::Stdio;
+use std::time::Duration;
+
+use async_trait::async_trait;
+use serde_json::json;
+use tokio::io::AsyncReadExt;
+use tokio::process::Command;
+use tokio::time::timeout;
+
+use crate::tools::traits::{Tool, ToolResult};
+
+const MAX_TIMEOUT_SECS: u64 = 600;
+const MAX_OUTPUT_CHARS: usize = 50_000;
+
+pub struct BashTool {
+    timeout_secs: u64,
+    working_dir: Option<String>,
+    deny_patterns: Vec<String>,
+}
+
+impl BashTool {
+    pub fn new() -> Self {
+        Self {
+            timeout_secs: 60,
+            working_dir: None,
+            deny_patterns: vec![
+                r"\brm\s+-[rf]{1,2}\b".to_string(),
+                r"\bdel\s+/[fq]\b".to_string(),
+                r"\brmdir\s+/s\b".to_string(),
+                r":\(\)\s*\{.*\};\s*:".to_string(),
+            ],
+        }
+    }
+
+    pub fn with_timeout(mut self, timeout_secs: u64) -> Self {
+        self.timeout_secs = timeout_secs;
+        self
+    }
+
+    pub fn with_working_dir(mut self, dir: String) -> Self {
+        self.working_dir = Some(dir);
+        self
+    }
+
+    fn guard_command(&self, command: &str) -> Option<String> {
+        let lower = command.to_lowercase();
+        for pattern in &self.deny_patterns {
+            if regex::Regex::new(pattern)
+                .ok()
+                .map(|re| re.is_match(&lower))
+                .unwrap_or(false)
+            {
+                return Some(format!(
+                    "Command blocked by safety guard (dangerous pattern: {})",
+                    pattern
+                ));
+            }
+        }
+        None
+    }
+
+    fn truncate_output(&self, output: &str) -> String {
+        if output.len() <= MAX_OUTPUT_CHARS {
+            return output.to_string();
+        }
+
+        let half = MAX_OUTPUT_CHARS / 2;
+        format!(
+            "{}...\n\n(... {} chars truncated ...)\n\n{}",
+            &output[..half],
+            output.len() - MAX_OUTPUT_CHARS,
+            &output[output.len() - half..]
+        )
+    }
+}
+
+impl Default for BashTool {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+#[async_trait]
+impl Tool for BashTool {
+    fn name(&self) -> &str {
+        "bash"
+    }
+
+    fn description(&self) -> &str {
+        "Execute a bash shell command and return its output. Use with caution."
+    }
+
+    fn parameters_schema(&self) -> serde_json::Value {
+        json!({
+            "type": "object",
+            "properties": {
+                "command": {
+                    "type": "string",
+                    "description": "The shell command to execute"
+                },
+                "timeout": {
+                    "type": "integer",
+                    "description": format!("Timeout in seconds (default {}, max {})", self.timeout_secs, MAX_TIMEOUT_SECS),
+                    "minimum": 1,
+                    "maximum": MAX_TIMEOUT_SECS
+                }
+            },
+            "required": ["command"]
+        })
+    }
+
+    fn exclusive(&self) -> bool {
+        true // Shell commands should not run concurrently
+    }
+
+    async fn execute(&self, args: serde_json::Value) -> anyhow::Result<ToolResult> {
+        let command = match args.get("command").and_then(|v| v.as_str()) {
+            Some(c) => c,
+            None => {
+                return Ok(ToolResult {
+                    success: false,
+                    output: String::new(),
+                    error: Some("Missing required parameter: command".to_string()),
+                });
+            }
+        };
+
+        // Safety check
+        if let Some(error) = self.guard_command(command) {
+            return Ok(ToolResult {
+                success: false,
+                output: String::new(),
+                error: Some(error),
+            });
+        }
+
+        let timeout_secs = args
+            .get("timeout")
+            .and_then(|v| v.as_u64())
+            .unwrap_or(self.timeout_secs)
+            .min(MAX_TIMEOUT_SECS);
+
+        let cwd = self
+            .working_dir
+            .as_ref()
+            .map(|d| Path::new(d))
+            .unwrap_or_else(|| Path::new("."));
+
+        let result = timeout(
+            Duration::from_secs(timeout_secs),
+            self.run_command(command, cwd),
+        )
+        .await;
+
+        match result {
+            Ok(Ok(output)) => Ok(ToolResult {
+                success: true,
+                output,
+                error: None,
+            }),
+            Ok(Err(e)) => Ok(ToolResult {
+                success: false,
+                output: String::new(),
+                error: Some(e),
+            }),
+            Err(_) => Ok(ToolResult {
+                success: false,
+                output: String::new(),
+                error: Some(format!(
+                    "Command timed out after {} seconds",
+                    timeout_secs
+                )),
+            }),
+        }
+    }
+}
+
+impl BashTool {
+    async fn run_command(&self, command: &str, cwd: &Path) -> Result<String, String> {
+        let mut cmd = Command::new("bash");
+        cmd.args(["-c", command])
+            .stdout(Stdio::piped())
+            .stderr(Stdio::piped())
+            .current_dir(cwd);
+
+        let mut child = cmd.spawn().map_err(|e| format!("Failed to spawn: {}", e))?;
+
+        let mut stdout = Vec::new();
+        let mut stderr = Vec::new();
+
+        if let Some(ref mut out) = child.stdout {
+            out.read_to_end(&mut stdout)
+                .await
+                .map_err(|e| format!("Failed to read stdout: {}", e))?;
+        }
+
+        if let Some(ref mut err) = child.stderr {
+            err.read_to_end(&mut stderr)
+                .await
+                .map_err(|e| format!("Failed to read stderr: {}", e))?;
+        }
+
+        let status = child
+            .wait()
+            .await
+            .map_err(|e| format!("Failed to wait: {}", e))?;
+
+        let mut output = String::new();
+
+        if !stdout.is_empty() {
+            let stdout_str = String::from_utf8_lossy(&stdout);
+            output.push_str(&stdout_str);
+        }
+
+        if !stderr.is_empty() {
+            let stderr_str = String::from_utf8_lossy(&stderr);
+            if !stderr_str.trim().is_empty() {
+                if !output.is_empty() {
+                    output.push_str("\n");
+                }
+                output.push_str("STDERR:\n");
+                output.push_str(&stderr_str);
+            }
+        }
+
+        output.push_str(&format!("\nExit code: {}", status.code().unwrap_or(-1)));
+
+        Ok(self.truncate_output(&output))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    async fn test_simple_command() {
+        let tool = BashTool::new();
+        let result = tool
+            .execute(json!({ "command": "echo 'Hello World'" }))
+            .await
+            .unwrap();
+
+        assert!(result.success);
+        assert!(result.output.contains("Hello World"));
+    }
+
+    #[tokio::test]
+    async fn test_pwd_command() {
+        let tool = BashTool::new();
+        let result = tool
+            .execute(json!({ "command": "pwd" }))
+            .await
+            .unwrap();
+
+        assert!(result.success);
+    }
+
+    #[tokio::test]
+    async fn test_ls_command() {
+        let tool = BashTool::new();
+        let result = tool.execute(json!({ "command": "ls -la /tmp" })).await.unwrap();
+
+        assert!(result.success);
+    }
+
+    #[tokio::test]
+    async fn test_dangerous_rm() {
+        let tool = BashTool::new();
+        let result = tool
+            .execute(json!({ "command": "rm -rf /" }))
+            .await
+            .unwrap();
+
+        assert!(!result.success);
+        assert!(result.error.unwrap().contains("blocked"));
+    }
+
+    #[tokio::test]
+    async fn test_dangerous_fork_bomb() {
+        let tool = BashTool::new();
+        let result = tool
+            .execute(json!({ "command": ":(){ :|:& };:" }))
+            .await
+            .unwrap();
+
+        assert!(!result.success);
+        assert!(result.error.unwrap().contains("blocked"));
+    }
+
+    #[tokio::test]
+    async fn test_missing_command() {
+        let tool = BashTool::new();
+        let result = tool.execute(json!({})).await.unwrap();
+
+        assert!(!result.success);
+        assert!(result.error.unwrap().contains("command"));
+    }
+
+    #[tokio::test]
+    async fn test_timeout() {
+        let tool = BashTool::new();
+        let result = tool
+            .execute(json!({
+                "command": "sleep 10",
+                "timeout": 1
+            }))
+            .await
+            .unwrap();
+
+        assert!(!result.success);
+        assert!(result.error.unwrap().contains("timed out"));
+    }
+}
diff --git a/src/tools/mod.rs b/src/tools/mod.rs
index cd94be7..ecb4849 100644
--- a/src/tools/mod.rs
+++ b/src/tools/mod.rs
@@ -1,3 +1,4 @@
+pub mod bash;
 pub mod calculator;
 pub mod file_edit;
 pub mod file_read;
@@ -6,6 +7,7 @@ pub mod registry;
 pub mod schema;
 pub mod traits;
 
+pub use bash::BashTool;
 pub use calculator::CalculatorTool;
 pub use file_edit::FileEditTool;
 pub use file_read::FileReadTool;