diff --git a/src/erc7730/convert/calldata/convert_erc7730_v2_input_to_calldata.py b/src/erc7730/convert/calldata/convert_erc7730_v2_input_to_calldata.py
index 2fa53156..c769958c 100644
--- a/src/erc7730/convert/calldata/convert_erc7730_v2_input_to_calldata.py
+++ b/src/erc7730/convert/calldata/convert_erc7730_v2_input_to_calldata.py
@@ -101,6 +101,23 @@
 ADDRESS_LENGTH = 20
 
 
+def _describe(input_descriptor: InputERC7730Descriptor, source: HttpUrl | None) -> str:
+    """Name a descriptor in a diagnostic.
+
+    ``source`` is optional and is None for a local file, which is the usual case for the CLI,
+    so fall back to what the descriptor calls itself -- the same identifier the converted
+    output carries as its contract name.
+
+    :param input_descriptor: descriptor being converted
+    :param source: source URL, if one was supplied
+    :return: the most specific identifier available
+    """
+    name = input_descriptor.metadata.contractName or getattr(input_descriptor.context, "id", None)
+    if name is not None and source is not None:
+        return f"{name} ({source})"
+    return str(name or source or "<unidentified>")
+
+
 def erc7730_v2_descriptor_to_calldata_descriptors(
     input_descriptor: InputERC7730Descriptor,
     source: HttpUrl | None = None,
@@ -190,7 +207,7 @@ def erc7730_v2_descriptor_to_calldata_descriptors(
         return output_descriptors
 
     except Exception as e:
-        out.warning(f"Error processing v2 ERC-7730 file {source}, skipping it")
+        out.warning(f"Error processing v2 ERC-7730 descriptor {_describe(input_descriptor, source)}, skipping it")
         exception_to_output(e, out)
 
     return []
diff --git a/tests/v2/convert/calldata/test_describe.py b/tests/v2/convert/calldata/test_describe.py
new file mode 100644
index 00000000..6ccf2497
--- /dev/null
+++ b/tests/v2/convert/calldata/test_describe.py
@@ -0,0 +1,51 @@
+from typing import Any
+
+import pytest
+from pydantic_string_url import HttpUrl
+
+from erc7730.convert.calldata.convert_erc7730_v2_input_to_calldata import _describe
+from erc7730.model.input.v2.descriptor import InputERC7730Descriptor
+
+SOURCE = HttpUrl("https://example.com/calldata-MyContract.json")
+
+
+def descriptor(*, context_id: str | None = None, contract_name: str | None = None) -> InputERC7730Descriptor:
+    context: dict[str, Any] = {
+        "contract": {"deployments": [{"chainId": 1, "address": "0x0000000000000000000000000000000000000001"}]}
+    }
+    if context_id is not None:
+        context["$id"] = context_id
+    metadata: dict[str, Any] = {"owner": "Someone"}
+    if contract_name is not None:
+        metadata["contractName"] = contract_name
+    return InputERC7730Descriptor.model_validate(
+        {"context": context, "metadata": metadata, "display": {"formats": {}}}, strict=True
+    )
+
+
+def test_the_contract_name_is_preferred() -> None:
+    assert _describe(descriptor(context_id="Fallback", contract_name="MyContract"), None) == "MyContract"
+
+
+def test_the_context_id_is_the_fallback() -> None:
+    """A descriptor need not set contractName, and $id is what the output falls back to as well."""
+    assert _describe(descriptor(context_id="MyContract"), None) == "MyContract"
+
+
+def test_a_source_is_kept_beside_the_name() -> None:
+    """Both identify it, and a batch run over many files wants the path as well as the name."""
+    assert _describe(descriptor(contract_name="MyContract"), SOURCE) == f"MyContract ({SOURCE})"
+
+
+def test_the_source_alone_is_used_when_the_descriptor_names_nothing() -> None:
+    assert _describe(descriptor(), SOURCE) == str(SOURCE)
+
+
+def test_neither_is_stated_rather_than_printing_none() -> None:
+    """The old message read "file None", which named nothing at all."""
+    assert _describe(descriptor(), None) == "<unidentified>"
+
+
+@pytest.mark.parametrize("source", [None, SOURCE])
+def test_it_never_returns_none_as_text(source: HttpUrl | None) -> None:
+    assert "None" not in _describe(descriptor(), source)