Show Structure

1"""Show JSON keys and types without values. Reads from stdin or a file argument."""
2
3import json
4import sys
5
6
7def load_trace_data(source):
8    raw = json.load(source)
9    # Claude Code persists large MCP tool results as [{"type": "text", "text": "<json>"}] — unwrap to get the actual trace data.
10    if isinstance(raw, list) and raw and isinstance(raw[0], dict) and raw[0].get("type") == "text":
11        raw = json.loads(raw[0]["text"])
12    return raw
13
14
15def structure(obj, depth=0, max_depth=3):
16    indent = "  " * depth
17    if depth > max_depth:
18        print(f"{indent}...")
19        return
20    if isinstance(obj, dict):
21        for k, v in obj.items():
22            if isinstance(v, dict):
23                print(f"{indent}{k}: {{...}} ({len(v)} keys)")
24                structure(v, depth + 1, max_depth)
25            elif isinstance(v, list):
26                print(f"{indent}{k}: [...] ({len(v)} items)")
27                if v:
28                    structure(v[0], depth + 1, max_depth)
29            elif isinstance(v, str):
30                print(f"{indent}{k}: str[{len(v)}]")
31            else:
32                print(f"{indent}{k}: {v}")
33    elif isinstance(obj, list):
34        print(f"{indent}[{len(obj)} items]")
35        if obj:
36            structure(obj[0], depth + 1, max_depth)
37
38
39if len(sys.argv) > 1:
40    with open(sys.argv[1]) as f:
41        data = load_trace_data(f)
42else:
43    data = load_trace_data(sys.stdin)
44structure(data)