rohitg00/ai-engineering-from-scratch · error · ValueError

review_sample must contain text

Error message

review_sample must contain text

What it means

The final content check: the sampling response's content object must carry a 'text' string. An image/audio content object, a content dict without 'text', or text of the wrong type fails here after every earlier check has passed.

Source

Thrown at certifications/claude/lessons/11-mcp-server-design-and-integration/code/main.py:425

        elicitation = responses["review_goal"]
        if not all(
            isinstance(response, dict)
            for response in (workspace_scope, review_sample, elicitation)
        ):
            raise ValueError("inputResponses entries must be objects")
        elicitation_content = elicitation.get("content", {})
        if not isinstance(elicitation_content, dict):
            raise ValueError("review_goal.content must be an object")
        roots = workspace_scope.get("roots")
        sample_content = review_sample.get("content", {})
        goal = elicitation_content.get("goal")
        if not isinstance(roots, list) or not isinstance(sample_content, dict):
            raise ValueError("inputResponses contain invalid roots or sampling results")
        if elicitation.get("action") != "accept" or not isinstance(goal, str):
            raise ValueError("review_goal must be accepted with a string goal")
        sample = sample_content.get("text")
        if not isinstance(sample, str):
            raise ValueError("review_sample must contain text")
        summary = {
            "goal": goal,
            "rootCount": len(roots),
            "sample": sample,
            "topic": arguments["topic"],
        }
        return self._complete(
            content=[{"type": "text", "text": json.dumps(summary, sort_keys=True)}],
            isError=False,
        )

    @staticmethod
    def _progress(token: str | int, progress: int, total: int, message: str) -> dict[str, Any]:
        return {
            "jsonrpc": "2.0",
            "method": "notifications/progress",
            "params": {
                "progressToken": token,

View on GitHub (pinned to 39ea8a1c6d)

Solutions

1. Return text content: {"content": {"type": "text", "text": "..."}}
2. When sampling can yield images, request or force text-only output for this tool
3. Fail fast on missing text rather than sending an incomplete response

Example fix

# before
review_sample = {"content": {"type": "image", "data": "..."}}

# after
review_sample = {"content": {"type": "text", "text": "review focus: auth errors"}}

text = responses["review_sample"].get("content", {}).get("text")
if not isinstance(text, str):
    raise ValueError("sampling response must contain text content")

def has_text_content(sample: object) -> bool:
    return (
        isinstance(sample, dict)
        and isinstance(sample.get("content"), dict)
        and isinstance(sample["content"].get("text"), str)
    )

When it happens

Trigger: review_sample content like {"type": "image", ...} or {"content": {}} — any createMessage result whose content lacks a string 'text' field.

Common situations: A model or sampling stub returns multimodal content; a client normalizes text away; an empty sampling result forwarded unchanged.

Related errors

• inputResponses contain invalid roots or sampling results
• -32600
• -32603
• _meta.{PROTOCOL_VERSION_KEY} is required
• _meta.{CLIENT_CAPABILITIES_KEY} is required

AI-assisted analysis of rohitg00/ai-engineering-from-scratch@39ea8a1c6d (2026-08-26). Data as JSON: /api/errors/fb3fc5e2a73b6252. Report an issue: GitHub.