Environment:

• OpenClaw: 2026.4.15 (041266a)
• Node: v22.22.0
• OS: Linux 6.17.0-1010-aws (aarch64, Ubuntu 24.04)
• Provider: Amazon Bedrock
• Model: global.anthropic.claude-opus-4-6-v1

Bug Description:
When generating tool calls with large content (e.g., writing a ~5KB markdown file via write or exec), the model emits tool calls with empty arguments {}, causing validation failures:

Validation failed for tool "write":
  - path: must have required property 'path'
  - content: must have required property 'content'

Received arguments: {}

and

Validation failed for tool "exec":
  - command: must have required property 'command'

Received arguments: {}

Reproduction:

1. Ask the assistant to create a comprehensive markdown analysis file (~5-7KB content)
2. The write tool call is emitted with empty {} arguments
3. Falling back to exec (e.g., cat << EOF > file) also produces empty {} arguments
4. The pattern repeats consistently across multiple retries and sessions

Scale of Impact:
In our case, this bug triggered 35+ consecutive failures across multiple sessions (write ~4 failures, exec ~30+ failures) before eventually succeeding. The same task with shorter content works fine.

Possible Causes:

1. Model output token truncation causing incomplete JSON serialization of tool arguments
2. Bedrock streaming may be dropping the tool_use content block when it exceeds a size threshold
3. Gateway may not be handling partial/malformed tool_use blocks gracefully

Expected Behavior:

• If tool arguments are truncated or empty, Gateway should retry or surface a clear error rather than repeatedly attempting the same pattern
• Ideally, large content should be chunked or handled via a temp file approach automatically

Workaround:
Eventually succeeded by retrying enough times. Breaking the content into smaller chunks or using exec with heredoc sometimes works, but is unreliable.