Add a 2 or 4 space indent option to process_json

docs/tool-guide.md

@@ -13,9 +13,9 @@ with ties ordered by first appearance. Lines follow `str.splitlines()`:
 empty input has zero lines and a final newline does not add an extra line.
 Sentence counting is a simple split on `.`, `!`, and `?`, not language-aware analysis.
 
-## process_json(text, action="format", sort_keys=False)
+## process_json(text, action="format", sort_keys=False, indent=2)
 
-Actions are `validate`, `format`, and `minify`. Formatting uses two spaces.
+Actions are `validate`, `format`, and `minify`. Formatting uses two spaces by default; pass `indent=4` for four spaces (`indent` accepts only 2 or 4 and is validated for every action, even though it only affects formatted output).
 `process_json('{"a": 1}', action="minify")` returns
 `{"valid": True, "output": '{"a":1}'}`. Validation returns only `valid` on success.
 Malformed input returns `{"valid": False, "error": "..."}`.

src/mcp_tools_lab/tools/json_tool.py

@@ -20,17 +20,25 @@ def process_json(
     text: str,
     action: Literal["validate", "format", "minify"] = "format",
     sort_keys: bool = False,
+    indent: int = 2,
 ) -> dict:
-    """Validate or format JSON using Python numbers; pretty output uses two spaces."""
+    """Validate or format JSON using Python numbers.
+
+    Pretty output (action="format") uses `indent` spaces; only 2 or 4 are
+    supported, defaulting to 2. `indent` must still be valid (2 or 4) for
+    every action, even when it does not affect minify or validate output.
+    """
     if action not in {"validate", "format", "minify"}:
         raise ValueError("action must be validate, format, or minify.")
+    if indent not in (2, 4):
+        raise ValueError("indent must be 2 or 4.")
     try:
         value = json.loads(text, parse_constant=_reject_constant, parse_float=_finite_float)
         if action == "validate":
             return {"valid": True}
         output = json.dumps(
             value, ensure_ascii=False, sort_keys=sort_keys, allow_nan=False,
-            indent=2 if action == "format" else None,
+            indent=indent if action == "format" else None,
             separators=None if action == "format" else (",", ":"),
         )
         return {"valid": True, "output": output}

tests/test_json_tool.py

@@ -22,3 +22,23 @@ def test_scalar_and_container_validation(text):
 def test_unknown_action():
     with pytest.raises(ValueError, match="action"):
         process_json("{}", "unknown")
+def test_default_indent_is_two_spaces():
+    assert process_json('{"a":1}')["output"] == '{\n  "a": 1\n}'
+    assert process_json('{"a":1}', indent=2)["output"] == '{\n  "a": 1\n}'
+def test_indent_four():
+    assert process_json('{"a":1}', indent=4)["output"] == '{\n    "a": 1\n}'
+def test_nested_indent():
+    result = process_json('{"outer":{"inner":1}}', indent=4)
+    assert result["output"] == '{\n    "outer": {\n        "inner": 1\n    }\n}'
+    result = process_json('{"outer":{"inner":1}}')
+    assert result["output"] == '{\n  "outer": {\n    "inner": 1\n  }\n}'
+def test_indent_is_validated_for_every_action():
+    with pytest.raises(ValueError, match="indent"):
+        process_json("{}", "minify", indent=3)
+    with pytest.raises(ValueError, match="indent"):
+        process_json("{}", "validate", indent=0)
+    with pytest.raises(ValueError, match="indent"):
+        process_json("{}", indent=-2)
+    # Valid indent keeps existing minify and validate behavior unchanged.
+    assert process_json('{"a":1}', "minify", indent=4)["output"] == '{"a":1}'
+    assert process_json('{"a":1}', "validate", indent=4) == {"valid": True}