question tool: model omits required "question" field on multi-question calls, producing SchemaError

Description

Summary

When the question tool is called with multiple items in the questions array,
the model (amazon-bedrock/eu.anthropic.claude-sonnet-4-6) occasionally omits
the required "question" field on one or more items. This causes a runtime
SchemaError and the span is recorded as an error in OTel tracing.

Error message

The question tool was called with invalid arguments: SchemaError(Missing key at ["questions"][1]["question"]). Please rewrite the input so it satisfies the expected schema.

Impact
Every occurrence is recorded as an error span (otelcol.signal: traces, status ERROR)
Inflates opencode.tool.question error rate in OTel/SigNoz dashboards
The question is never surfaced to the user; the interaction is silently lost
Environment
Model: amazon-bedrock/eu.anthropic.claude-sonnet-4-6
Observed via OTel tracing (SigNoz, collector otel/opentelemetry-collector-contrib:0.139.0)
Suggested fix
Add a retry-on-schema-error path that asks the model to correct and resubmit the malformed call
And/or strengthen the system prompt to remind the model that "question" is required on every array item

Plugins

No response

OpenCode version

Version 1.18.23 (1.18.23)

Steps to reproduce

Minimal reproduction

The following tool call input triggers the error — second item is missing "question":

{
  "questions": [
    {
      "header": "Database schema",
      "question": "Which database should we use for the new service?",
      "options": [
        { "label": "PostgreSQL", "description": "Relational, ACID-compliant, good for structured data." },
        { "label": "MongoDB", "description": "Document store, flexible schema, good for unstructured data." }
      ]
    },
    {
      "header": "Caching strategy",
      "options": [
        { "label": "Redis", "description": "In-memory, fast, good for session data." },
        { "label": "No cache", "description": "Keep it simple, query DB directly." }
      ]
    }
  ]
}

Verification
A manually constructed call with "question" present on both items succeeds with no error. The bug is generative — the model drops the field; the schema validator catches it correctly.


### Screenshot and/or share link

_No response_

### Operating System

MacOS 26.6.2

### Terminal

Warp