diff --git a/agentrace/cli.py b/agentrace/cli.py
index c7cda50..cacf1fb 100644
--- a/agentrace/cli.py
+++ b/agentrace/cli.py
@@ -122,8 +122,21 @@ def cmd_show(args) -> int:
     if not match:
         console.print(f"[red]No run matching {args.id!r}[/]")
         return 1
-    r = match[0]
-    console.print(f"[bold]{escape(r.description)}[/]  [dim]{escape(r.tool_use_id)}[/]")
+    exact = next((r for r in match if r.tool_use_id == args.id), None)
+    if exact is not None:
+        r = exact
+    elif len(match) > 1:
+        console.print(f"[red]Run ID {args.id!r} is ambiguous. Matching runs:[/]")
+        for candidate in match:
+            description = candidate.description or "(none)"
+            console.print(f"  {escape(candidate.tool_use_id)}  {escape(description)}")
+        console.print("Please provide a more specific run ID.")
+        return 1
+    else:
+        r = match[0]
+    console.print(
+        f"[bold]{escape(r.description or '(none)')}[/]  [dim]{escape(r.tool_use_id)}[/]"
+    )
     console.print(f"[dim]duration: {r.duration_s}s | background: {r.background}[/]\n")
     console.print("[bold cyan]PROMPT[/]")
     console.print(escape(r.prompt[: args.max]) if r.prompt[: args.max] else "[dim](empty)[/]")
diff --git a/tests/test_agentrace.py b/tests/test_agentrace.py
index 22ce91a..24a6743 100644
--- a/tests/test_agentrace.py
+++ b/tests/test_agentrace.py
@@ -11,8 +11,10 @@
 from __future__ import annotations
 
 import json
+from argparse import Namespace
 from datetime import UTC, datetime, timedelta
 
+from agentrace import cli
 from agentrace.checks import analyse
 from agentrace.parse import AgentRun, parse_session
 
@@ -192,6 +194,39 @@ def test_tool_use_without_id_is_skipped(tmp_path):
     assert s.runs == []
 
 
+# --------------------------------------------------------------------------- show
+
+
+def test_show_rejects_ambiguous_short_id(monkeypatch, capsys):
+    runs = [
+        _run(tool_use_id="toolu_alpha_shared", description="alpha"),
+        _run(tool_use_id="toolu_beta_shared", description=None),
+    ]
+    monkeypatch.setattr(cli, "_load", lambda args: runs)
+
+    assert cli.cmd_show(Namespace(id="shared", max=4000)) == 1
+    output = capsys.readouterr().out
+    assert "ambiguous" in output
+    assert "toolu_alpha_shared" in output
+    assert "alpha" in output
+    assert "toolu_beta_shared" in output
+    assert "(none)" in output
+
+
+def test_show_prefers_exact_id_over_suffix_match(monkeypatch, capsys):
+    runs = [
+        _run(tool_use_id="shared", description=None),
+        _run(tool_use_id="toolu_other_shared", description="other"),
+    ]
+    monkeypatch.setattr(cli, "_load", lambda args: runs)
+
+    assert cli.cmd_show(Namespace(id="shared", max=4000)) == 0
+    output = capsys.readouterr().out
+    assert "(none)" in output
+    assert "shared" in output
+    assert "toolu_other_shared" not in output
+
+
 # --------------------------------------------------------------------------- checks