fix(bedrock): drop strict/additionalProperties from toolSpec for Sonnet 4.6 and Haiku 4.5

[nickhac]

TLDR

Problem this solves:

• Claude Sonnet 4.6 and Haiku 4.5 on Bedrock Converse reject toolSpec.strict, producing a compiled-grammar error (>300MB) and a 504 Gateway Timeout for the caller
• LiteLLM has been forwarding strict and additionalProperties to these models since v1.90.0

How it solves it:

• Sets bedrock_converse_supports_strict_tools: false on all regional Bedrock Converse entries for Sonnet 4.6 and Haiku 4.5 (14 entries each file)
• Same fix pattern already applied for Opus 4.7/4.8 (fix(bedrock/converse): drop toolSpec.strict for Opus 4.7/4.8 (#31582) #31923) and Sonnet 4 (fix(bedrock): drop strict/additionalProperties from toolSpec for Claude Sonnet 4 #31943)

Relevant issues

Closes #34388

Type

• Bug Fix

Changes

• model_prices_and_context_window.json — add bedrock_converse_supports_strict_tools: false to 14 regional Bedrock entries for Sonnet 4.6 and Haiku 4.5
• litellm/model_prices_and_context_window_backup.json — same change to backup file
• tests/test_litellm/litellm_core_utils/prompt_templates/test_bedrock_converse_strict_tools_opus_47_48.py — extend existing regression tests to cover Sonnet 4.6 and Haiku 4.5; correct a wrong assertion that previously claimed Sonnet 4.6 keeps strict forwarded

Testing

pytest tests/test_litellm/litellm_core_utils/prompt_templates/test_bedrock_converse_strict_tools_opus_47_48.py -v
# 43 passed (was 26 before this fix)

The 17 new test cases confirm:

• strict is dropped from toolSpec for all Sonnet 4.6 and Haiku 4.5 model IDs
• additionalProperties is dropped from the input schema for these models
• bedrock_converse_supports_strict_tools flag is correctly set in the model cost map
• The helper function bedrock_converse_supports_strict_tools() returns False for these models

Screenshots / Proof of Fix

Before this fix, _bedrock_tools_pt with a strict tool and model anthropic.claude-sonnet-4-6 returns:

{'inputSchema': {'json': {'additionalProperties': False, ...}}, 'name': 'get_weather', 'strict': True}
# strict leaks through → Bedrock returns grammar-size error → 504 timeout

After this fix:

{'inputSchema': {'json': {...}}, 'name': 'get_weather', 'description': '...'}
# strict and additionalProperties stripped → Bedrock accepts the request

Pre-submission checklist

• Tests added (17 new parametrized test cases in existing regression test file)
• CI passes locally (pytest — 43 passed, 0 failed)
• Scope isolated: extends existing fix pattern, no new abstractions
• Both model_prices_and_context_window.json and backup file updated

AI Assistance Disclosure

This contribution was AI-assisted using Hermes Agent (Nous Research).

Co-authored-by: Hermes Agent hermes-agent@nousresearch.com

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[nickhac]

Note for reviewer: Greptile initially could not summarise this PR because the branch base was stale (fork not synced to upstream). That is now fixed — the diff is clean: 3 files, 75 insertions, 7 deletions, identical in shape to #31943 (Sonnet 4 fix).

What this PR does in one sentence: extends the existing bedrock_converse_supports_strict_tools: false opt-out (already applied in #31923 for Opus 4.7/4.8 and #31943 for Sonnet 4) to Claude Sonnet 4.6 and Claude Haiku 4.5, which exhibit the same compiled-grammar overflow error when toolSpec.strict is forwarded.

Files changed:

• model_prices_and_context_window.json — adds flag to 6 Sonnet 4.6 regional entries + 8 Haiku 4.5 regional entries
• litellm/model_prices_and_context_window_backup.json — same
• test_bedrock_converse_strict_tools_opus_47_48.py — extends existing regression test parametrize lists; corrects a wrong assertion that previously claimed bedrock/us.anthropic.claude-sonnet-4-6 keeps strict forwarded (it does not — that is the bug)

Test result: 43 passed (was 26 before this PR), 0 failed.

[codspeed-hq]

Merging this PR will not alter performance

✅ 31 untouched benchmarks

---

_{Comparing nickhac:fix/bedrock-strict-tools-sonnet-4-6-haiku-4-5 (7c146bf) with main (714fff6)}

[nickhac]

@greptileai

[greptile-apps]

Greptile Summary

The PR disables unsupported strict tool schemas for Claude Sonnet 4.6 and Haiku 4.5 on Bedrock Converse.

• Adds the capability flag to every relevant regional model entry in both canonical and backup metadata.
• Extends regression coverage for model lookup, strict removal, and additionalProperties removal.
• Corrects the prior Sonnet 4.6 expectation while retaining positive coverage for supported Anthropic models.

Confidence Score: 5/5

The PR appears safe to merge, with the affected model variants consistently configured and covered by focused regression tests.

The canonical and fallback model maps remain synchronized, model-ID normalization reaches the new flags, and the changed tests verify both capability lookup and emitted Bedrock tool schemas.

Important Files Changed

Filename	Overview
model_prices_and_context_window.json	Adds the strict-tools capability override consistently to all relevant Sonnet 4.6 and Haiku 4.5 Bedrock Converse entries.
litellm/model_prices_and_context_window_backup.json	Mirrors the canonical model metadata changes so local fallback lookups preserve the corrected behavior.
tests/test_litellm/litellm_core_utils/prompt_templates/test_bedrock_converse_strict_tools_opus_47_48.py	Extends meaningful regression coverage without weakening the remaining supported-model assertions.

_{Reviews (1): Last reviewed commit: "fix(bedrock): drop strict/additionalProp..." | Re-trigger Greptile}