Port from cline/cline#11803: recursively normalize JSON-string tool args by schema

[teknium1]

Summary

Tool args now repair JSON-encoded values at every depth, not just the top level — so a model that emits {"todos": ["{\"id\":\"1\",...}"]} (array elements as JSON strings) gets a clean native list before the tool runs.

coerce_tool_args only normalized the outermost value. Three core tools have array<object> schemas — todo.todos, delegate_task.tasks, memory.operations — so when an open-weight model (DeepSeek, Qwen, GLM) emitted array elements or nested object fields as JSON strings, the raw strings flowed into the tool and failed downstream on item["id"] / item["goal"] access.

Ported from cline/cline#11803 ("Normalize JSON-like tool inputs by schema"), adapted to hermes-agent's existing Python coercion layer rather than added as a new module.

Changes

• model_tools.py: add _normalize_json_strings_for_schema() (recursive, schema-guided) + _schema_accepts_kind() helper. Wire it into coerce_tool_args for array/object-typed properties so nested array items and object sub-fields are normalized too. Top-level behavior unchanged.
• tests/run_agent/test_tool_arg_coercion.py: +27 tests (helpers, recursion, real todo schema, preservation cases).

Adaptation notes

• hermes-agent already had schema-aware top-level coercion (whole-array-as-string → list, scalar→number/bool, bare→single-element list). This PR only adds the missing recursion into array items and nested object properties — the one gap vs. Cline's implementation.
• Parsing stays schema-guided: a string is parsed only when the matching schema position expects an array/object, so a legitimate JSON-looking string field (type: string, e.g. a memory content value that happens to be JSON) is preserved verbatim.
• No new tool, no schema change, no env var. Pure normalization at the existing dispatch boundary.

Validation

Case	Before	After
todo.todos element as JSON string	['{"id":...}'] (raw string)	[{"id":...}]
delegate_task.tasks element as JSON string	raw string in list	parsed object
memory.operations element as JSON string	raw string in list	parsed object
memory content field = JSON-looking string	preserved	preserved (no over-parse)
native list / scalar coercion	works	unchanged

scripts/run_tests.sh tests/run_agent/test_tool_arg_coercion.py → 77 passed (50 existing + 27 new). E2E verified with real registry schemas via isolated HERMES_HOME.

Source: cline/cline#11803 (weekly Cline PR scout).

Infographic

[github-actions]

🔎 Lint report: cline-port/nested-tool-arg-coercion vs origin/main

ruff

Total: 0 on HEAD, 0 on base (➖ 0)

🆕 New issues: none

✅ Fixed issues: none

Unchanged: 0 pre-existing issues carried over.

ty (type checker)

Total: 11244 on HEAD, 11244 on base (➖ 0)

🆕 New issues: none

✅ Fixed issues: none

Unchanged: 5937 pre-existing issues carried over.

Diagnostics are surfaced as warnings — this check never fails the build.

[teknium1]

Merged via PR #52220.