KrustyPlanet/hermes-agent
6
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

fix(tools): wrap bare scalars in single-element list for array-typed args

Browse source 
Open-weight models (DeepSeek, Qwen, GLM) sometimes emit tool calls like
`{"urls": "https://a.com"}` when the tool schema declares
`type: array`.  The call was JSON-valid but semantically wrong, and
`coerce_tool_args` would pass the bare string through — the tool then
failed with a confusing type error.

`coerce_tool_args` now wraps non-list, non-null values in a
single-element list when the schema declares `array`.  Strings still go
through `_coerce_value` first so JSON-encoded arrays
(`'["a","b"]'`) parse correctly and nullable `"null"` still
becomes `None`.  `None` itself is preserved — tools with sensible
defaults already handle it, and we don't want to silently mask a
deliberate null.

Salvaged from #19652 (NikolayGusev-astra) — the broader validate-then-
repair layer had several issues (duplicated existing coercion,
mis-classified `old_string` as a path field, prepended non-JSON
prefixes to tool results that break downstream JSON parsing, hardcoded
offset/limit defaults unsuitable for non-read_file tools).  The one
genuinely new capability is wrapping bare scalars, which is implemented
here directly inside the existing coercion path.

Co-authored-by: Nikolay Gusev <ngusev@astralinux.ru>
This commit is contained in:
Nikolay Gusev 2026-05-04 04:58:35 -07:00 • committed by Teknium
parent 6f864f8f94
commit fdf9343c51
3 changed files with 98 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

41
model_tools.py
View file

@ -511,6 +511,12 @@ def coerce_tool_args(tool_name: str, args: Dict[str, Any]) -> Dict[str, Any]:
Handles ``"type": "integer"``, ``"type": "number"``, ``"type": "boolean"``,
and union types (``"type": ["integer", "string"]``).
Also wraps bare scalar values in a single-element list when the schema
declares ``"type": "array"``. Open-weight models (DeepSeek, Qwen, GLM)
sometimes emit ``{"urls": "https://a.com"}`` when the tool expects
``{"urls": ["https://a.com"]}``; wrapping here avoids a confusing tool
failure on what is otherwise a well-formed call.
"""
if not args or not isinstance(args, dict):
return args
@ -523,13 +529,42 @@ def coerce_tool_args(tool_name: str, args: Dict[str, Any]) -> Dict[str, Any]:
if not properties:
return args
for key, value in args.items():
if not isinstance(value, str):
continue
for key, value in list(args.items()):
prop_schema = properties.get(key)
if not prop_schema:
continue
expected = prop_schema.get("type")
# Wrap bare non-list values when the schema declares ``array``.
# Strings still go through _coerce_value first so JSON-encoded
# arrays (``'["a","b"]'``) get parsed and nullable ``"null"``
# becomes ``None`` rather than ``["null"]``.
# ``None`` itself is preserved — we don't know whether the model
# meant "omit" or "empty list", and tools with sensible defaults
# (e.g. read_file's normalize_read_pagination) already handle it.
if expected == "array" and value is not None and not isinstance(value, (list, tuple)):
if isinstance(value, str):
coerced = _coerce_value(value, expected, schema=prop_schema)
if coerced is not value:
# _coerce_value handled it (JSON-parsed list or
# nullable "null" → None).
args[key] = coerced
continue
args[key] = [value]
logger.info(
"coerce_tool_args: wrapped bare string in list for %s.%s",
tool_name, key,
)
continue
args[key] = [value]
logger.info(
"coerce_tool_args: wrapped bare %s in list for %s.%s",
type(value).__name__, tool_name, key,
)
continue
if not isinstance(value, str):
continue
if not expected and not _schema_allows_null(prop_schema):
continue
coerced = _coerce_value(value, expected, schema=prop_schema)