feat(bedrock): normalize custom tool JSON schema for Invoke and Converse

[Sameerlite]

Summary

Claude Code and the Anthropic Messages API send tool definitions with input_schema.type: "custom". Amazon Bedrock Invoke and Converse validate JSON Schema strictly and reject custom (and may reject missing/invalid root type).

Changes

• Introduce normalize_json_schema_custom_types_to_object in llms/bedrock/common_utils.py and reuse it for Bedrock Invoke (messages + chat invoke) transformations.
• Update _bedrock_tools_pt to accept Anthropic-style tools (name + input_schema), deep-copy parameters, normalize custom → object recursively, and coerce invalid root type to object for Converse toolSpec.inputSchema.json.

Tests

• test_normalize_tool_input_schema_types_for_bedrock_invoke, test_bedrock_invoke_messages_transform_converts_custom_tool_schema_type_to_object (tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py).
• test_bedrock_converse_tools_pt_converts_custom_schema_type_to_object (tests/llm_translation/test_bedrock_completion.py).

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Project	Deployment	Actions	Updated (UTC)
litellm	Ready	Preview, Comment	Apr 9, 2026 5:10am

[codspeed-hq]

Merging this PR will not alter performance

✅ 16 untouched benchmarks

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_{Comparing litellm_bedrock-normalize-custom-tool-schema (ec91021) with main (97f722f)}

[greptile-apps]

Greptile Summary

This PR normalizes Anthropic/Claude Code's type: \"custom\" in tool input_schema to standard JSON Schema types before sending to Amazon Bedrock, which strictly validates JSON Schema and rejects \"custom\". It covers both the Bedrock Converse path (_bedrock_tools_pt in factory.py) and the Bedrock Invoke path (normalize_tool_input_schema_types_for_bedrock_invoke in common_utils.py), and adds graceful handling of missing or blank tool names for both paths.

Confidence Score: 5/5

Safe to merge — core normalization logic is correct, deep-copies protect callers, and tests cover both Converse and Invoke paths end-to-end.

All findings are P2 style suggestions (inline imports without explanatory comments). No logic bugs, no data mutation of caller inputs, no missing guards, no security concerns, and tests are thorough.

No files require special attention.

Vulnerabilities

No security concerns identified. Changes are confined to schema normalization and tool-name sanitization in Bedrock request transformation, with no auth, secrets, or data-handling implications.

Important Files Changed

Filename	Overview
litellm/llms/bedrock/common_utils.py	Adds normalize_json_schema_custom_types_to_object (iterative, cycle-safe walker), normalize_tool_input_schema_types_for_bedrock_invoke, and ensure_bedrock_anthropic_messages_tool_names — all correct and well-documented.
litellm/litellm_core_utils/prompt_templates/factory.py	_bedrock_tools_pt extended to accept Anthropic-style tools (name+input_schema), deep-copies parameters, normalizes custom types, and coerces invalid root type to object; adds inline imports consistent with pre-existing pattern in the same function.
litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py	Wires up ensure_bedrock_anthropic_messages_tool_names alongside the existing normalize_tool_input_schema_types_for_bedrock_invoke call in transform_anthropic_messages_request.
litellm/llms/bedrock/chat/invoke_transformations/anthropic_claude3_transformation.py	Adds normalize_tool_input_schema_types_for_bedrock_invoke to _build_bedrock_anthropic_request_base for the chat/Invoke path; correct placement after remove_custom_field_from_tools.
litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py	Robustifies tool name handling in translate_anthropic_tools_to_openai — gracefully falls back to generated name when name is missing or blank.
tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py	Adds three pure-unit tests (no network) covering: schema type normalization, missing tool names, and end-to-end transform_anthropic_messages_request with custom types.
tests/llm_translation/test_bedrock_completion.py	Adds test_bedrock_converse_tools_pt_converts_custom_schema_type_to_object covering Converse path for both Anthropic-style and OpenAI-style tools with custom schema types.
tests/test_litellm/llms/anthropic/experimental_pass_through/adapters/test_anthropic_experimental_pass_through_adapters_transformation.py	No substantial changes visible in the diff for this file; no issues found.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Incoming tool definitions\nname + input_schema\nOR function.parameters] --> B{Bedrock path?}

    B --> |Converse _bedrock_tools_pt| C[copy.deepcopy parameters]
    B --> |Invoke AnthropicClaudeConfig| D[normalize_tool_input_schema_types_for_bedrock_invoke]

    C --> E[unpack_defs - expand $ref]
    E --> F[normalize_json_schema_custom_types_to_object]
    F --> G{root type valid?}
    G -->|No| H[set type = object]
    G -->|Yes| I[Build BedrockToolJsonSchemaBlock]
    H --> I

    D --> J[for each tool: normalize_json_schema_custom_types_to_object on input_schema]
    J --> K[ensure_bedrock_anthropic_messages_tool_names]
    K --> L[Bedrock Invoke request body]
    I --> M[Bedrock Converse request body]

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_{Reviews (2): Last reviewed commit: "fix(bedrock): custom tool schemas and mi..." | Re-trigger Greptile}

[krrish-berri-2]

what does this change do? @Sameerlite

[krrish-berri-2]

can you explain this?

[Sameerlite]

@krrish-berri-2 The code in adapters/transformation.py is used for /v1/messages → litellm.completion adapter flows. For Bedrock, that mainly means bedrock/converse/...