paperclipai/paperclip · error · ToolContentValidationError

prompt_injection_blocked

prompt_injection_blocked

Error message

Tool result contained prompt-injection instructions and was blocked

What it means

Prompt-injection guard in validateToolContent: the tool result matched injection patterns and promptInjectionMode is block (the default for results), so it is refused before reaching the model. The remote tool result embedding instruction-like text is at fault.

Source

Thrown at server/src/services/tool-content-guards.ts:245

}) {
  const sensitiveMode = input.sensitiveMode ?? "redact";
  const promptInjectionMode = input.promptInjectionMode ?? (input.direction === "result" ? "block" : "ignore");
  const redactedValue = isPlainObject(input.value) ? redactEventPayload(input.value) : input.value;
  const redactedSummary = summarizeToolValue(redactedValue);
  const findings: string[] = [];

  if (redactedSummary.redactedFields?.length) {
    findings.push("sensitive_value");
    if (sensitiveMode === "block") {
      throw new ToolContentValidationError("Tool content contains sensitive values", "sensitive_value_blocked", findings);
    }
  }

  const promptFindings = promptInjectionMode === "ignore" ? [] : scanPromptInjection(input.value);
  if (promptFindings.length > 0) {
    findings.push(...promptFindings);
    if (promptInjectionMode === "block") {
      throw new ToolContentValidationError(
        "Tool result contained prompt-injection instructions and was blocked",
        "prompt_injection_blocked",
        promptFindings,
      );
    }
  }

  return {
    value: redactedValue,
    summary: redactedSummary,
    findings,
  };
}

View on GitHub (pinned to 01ad858492)

Solutions

1. The tool result was blocked by the prompt-injection guard. Treat the source as untrusted; sanitize or avoid passing that content to the agent, and review the flagged patterns.

When it happens

Trigger: Thrown at server/src/services/tool-content-guards.ts:233 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of paperclipai/paperclip@01ad858492 (2026-08-18). Data as JSON: /api/errors/3ef4cace7b4dd910. Report an issue: GitHub.