Add pretty JSON output flag

README.md

@@ -33,6 +33,9 @@ cargo install arbitrum-cli
 # Query the latest block (JSON output, agent-ready)
 arbitrum-cli block latest
 
+# Query the latest block with indented JSON for debugging
+arbitrum-cli block latest --pretty
+
 # Check an address balance
 arbitrum-cli balance 0xC75020d5f669F5D15Afcb81b0e5F6d21bCDa9664
 
@@ -72,12 +75,15 @@ All commands default to JSON output. No flags, no ceremony — pipe it into `jq`
 # Agent-friendly
 arbitrum-cli balance 0xC750... | jq .balance_eth
 
+# Indented JSON for humans inspecting agent output
+arbitrum-cli balance 0xC750... --pretty
+
 # Generic RPC for agents — any method, any params
 arbitrum-cli exec eth_chainId --params '[]'
 arbitrum-cli exec eth_getLogs --params '[{"fromBlock":"latest","address":"0x..."}]'
 ```
 
-Use `--human` for colored terminal output when you're debugging.
+Use `--pretty` for indented JSON when you're debugging agent output. Use `--human` for colored terminal output.
 
 ## Create Protocol agent-deposit
 

src/main.rs

@@ -10,7 +10,7 @@ mod rpc;
     name = "arbitrum-cli",
     version,
     about = "Agent-first Arbitrum CLI — JSON in, JSON out, MCP-compatible",
-    long_about = "A single Rust binary to query Arbitrum, interact with contracts, monitor events, and expose an MCP server for AI agents. Default output is JSON (agent-friendly). Use --human for pretty terminal output."
+    long_about = "A single Rust binary to query Arbitrum, interact with contracts, monitor events, and expose an MCP server for AI agents. Default output is compact JSON (agent-friendly). Use --pretty for indented JSON or --human for colored terminal output."
 )]
 struct Cli {
     /// RPC URL (default: https://arb1.arbitrum.io/rpc)
@@ -21,6 +21,10 @@ struct Cli {
     #[arg(long, global = true)]
     human: bool,
 
+    /// Pretty-print JSON output with indentation
+    #[arg(long, global = true, conflicts_with = "human")]
+    pretty: bool,
+
     #[command(subcommand)]
     command: Commands,
 }
@@ -126,6 +130,8 @@ async fn main() -> eyre::Result<()> {
         .unwrap_or_else(|| "https://arb1.arbitrum.io/rpc".to_string());
     let out_mode = if cli.human {
         output::Mode::Human
+    } else if cli.pretty {
+        output::Mode::JsonPretty
     } else {
         output::Mode::Json
     };

src/output.rs

@@ -4,17 +4,25 @@ use serde_json::Value;
 #[derive(Clone, Copy, Debug)]
 pub enum Mode {
     Json,
+    JsonPretty,
     Human,
 }
 
 /// Emit a result to stdout in the requested mode.
 /// JSON mode: raw JSON for agents (default).
+/// JSON pretty mode: indented JSON for terminal debugging.
 /// Human mode: pretty colored output for terminals.
 pub fn emit(mode: Mode, label: &str, value: &Value) {
     match mode {
         Mode::Json => {
             println!("{}", serde_json::to_string(value).unwrap_or_default());
         }
+        Mode::JsonPretty => {
+            println!(
+                "{}",
+                serde_json::to_string_pretty(value).unwrap_or_default()
+            );
+        }
         Mode::Human => {
             println!("\n  {} {}", "✓".green().bold(), label.bold());
             println!("  {}", "─".repeat(50).dimmed());