Anthropic Data Handling Skill

Anthropic Data Handling

Overview

Handle data responsibly when building with Claude — manage the 200K token context window efficiently, implement conversation trimming strategies, redact PII before sending to the API, and configure data retention settings.

Context Window Management

Claude models have a 200K token context window. Managing it efficiently is critical.

// Count tokens before sending
const count = await client.messages.countTokens({
  model: 'claude-sonnet-4-20250514',
  messages,
  system: systemPrompt,
});

// Budget: 200K total - max_tokens (output) = available input
const MAX_CONTEXT = 200_000;
const MAX_OUTPUT = 4096;
const inputBudget = MAX_CONTEXT - MAX_OUTPUT;

if (count.input_tokens > inputBudget) {
  // Trim oldest messages, keep system prompt + recent context
  messages = trimToFit(messages, inputBudget);
}

Instructions

Step 1: Conversation Trimming

function trimConversation(messages: MessageParam[], maxTokens: number): MessageParam[] {
  // Always keep the first message (often contains key context)
  // Keep the most recent messages
  // Drop middle turns first
  if (messages.length <= 4) return messages;

  const first = messages[0];
  const recent = messages.slice(-6); // Last 3 turns
  return [first, ...recent];
}

PII Handling

// Strip PII before sending to Claude (if not needed for the task)
function redactPII(text: string): string {
  return text
    .replace(/\b[\w._%+-]+@[\w.-]+\.\w{2,}\b/g, '[EMAIL]')
    .replace(/\b\d{3}[-.]?\d{3}[-.]?\d{4}\b/g, '[PHONE]')
    .replace(/\b\d{3}-\d{2}-\d{4}\b/g, '[SSN]')
    .replace(/\b\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}\b/g, '[CARD]');
}

Data Retention

Default: Anthropic does not use API data for training
Zero retention: Available on Enterprise plans
Your responsibility: Don't store Claude responses containing user PII longer than needed

Output

Token counting implemented before sending requests (prevents context overflow errors)
Conversation trimming preserving first message and recent turns
PII redaction applied for emails, phone numbers, SSNs, and card numbers
Data retention policy documented and configured

Error Handling

| Error | Cause | Solution | |-------|-------|----------| | API Error | Check error type and status code | See clade-common-errors |

Examples

See Context Window Management (token counting + budget), Conversation Trimming function, and PII Handling regex patterns above.

Resources

Next Steps

See clade-enterprise-rbac for organization and access management.

Prerequisites

Completed clade-install-auth
Application handling user conversations or document processing
Understanding of token counting and context windows

Agent Skills: Anthropic Data Handling

Install this agent skill to your local

Skill Files