langchain-ai/deepagents · error · ValueError

`interpreter_ptc` list entries must be non-empty strings; go

Error message

`interpreter_ptc` list entries must be non-empty strings; got {entry!r}.

What it means

When interpreter_ptc is given as a list, _parse_interpreter_ptc requires every entry to be a non-empty string; entries like None, numbers, empty strings, or whitespace-only strings raise this error. This prevents silently allowing an unnamed or malformed tool.

Source

Thrown at libs/code/deepagents_code/config.py:2452

        normalized = raw.strip().lower()
        if normalized in {INTERPRETER_PTC_SAFE_SENTINEL, INTERPRETER_PTC_ALL_SENTINEL}:
            return normalized
        msg = (
            f"Invalid `interpreter_ptc` string {raw!r}; expected 'safe', 'all', "
            "or a list of tool names."
        )
        raise ValueError(msg)
    if isinstance(raw, list):
        if not raw:
            return False
        names: list[str] = []
        for entry in raw:
            if not isinstance(entry, str) or not entry.strip():
                msg = (
                    "`interpreter_ptc` list entries must be non-empty strings; "
                    f"got {entry!r}."
                )
                raise ValueError(msg)
            cleaned = entry.strip()
            if cleaned.lower() == INTERPRETER_PTC_ALL_SENTINEL:
                msg = (
                    "`interpreter_ptc` list entries cannot include 'all'; use "
                    "'all' as a standalone value or list explicit tool names "
                    "(optionally with the 'safe' preset)."
                )
                raise ValueError(msg)
            names.append(cleaned)
        return names
    msg = (
        f"`interpreter_ptc` must be False, 'safe', 'all', or a list of tool "
        f"names; got {type(raw).__name__}."
    )
    raise ValueError(msg)


@dataclass(frozen=True)

View on GitHub (pinned to a1af029e6e)

Solutions

Remove empty, whitespace-only, and non-string entries from the list.
Filter the list before writing it: [t for t in raw if isinstance(t, str) and t.strip()].
If disabling PTC, use the empty list [] or false rather than an entry of empties.

Example fix

// before
interpreter_ptc = ["bash", ""]
// after
interpreter_ptc = ["bash"]

Defensive patterns

Strategy: validation

Validate before calling

if isinstance(raw, str):
    raw = [t for t in raw.split(",") if t.strip()]
if isinstance(raw, list):
    raw = [t for t in raw if isinstance(t, str) and t.strip()]

Type guard

def is_valid_tool_list(v: object) -> bool:
    return isinstance(v, list) and all(isinstance(t, str) and t.strip() for t in v)

Try / catch

try:
    ptc = _parse_interpreter_ptc(raw_list)
except ValueError as e:
    logger.error("bad interpreter_ptc list: %s", e)
    ptc = False

Prevention

Filter empty strings when splitting comma-separated input
Coerce TOML arrays to clean string lists at load time
Reject null/numeric placeholders instead of passing them through

When it happens

Trigger: Passing interpreter_ptc = ["bash", "", 42] or ["bash", None] in config, or building the list programmatically with empty/whitespace entries from splitting an input string.

Common situations: Parsing a comma-separated env var with str.split(',') producing empty strings ('a,,b'), TOML arrays with placeholder empties, or generated configs inserting nulls.

Related errors

AI-assisted analysis of langchain-ai/deepagents@a1af029e6e (2026-08-29). Data as JSON: /api/errors/223494ba9bb48ccb. Report an issue: GitHub.