Grammarly Observability

Overview

Grammarly API integrations process user text through scoring, AI rewriting, and plagiarism endpoints where latency and accuracy directly affect user experience. Monitor text check response times, suggestion quality signals, API error rates, and token consumption to stay within rate limits. Catching degradation early prevents users from seeing stale suggestions or silent failures in real-time editing flows.

Key Metrics

Metric	Type	Target	Alert Threshold
Text check latency p95	Histogram	< 300ms	> 800ms
API error rate	Gauge	< 1%	> 5%
Suggestion acceptance rate	Gauge	> 40%	< 20% (quality signal)
Token usage (daily)	Counter	< 80% quota	> 90% quota
Plagiarism check latency	Histogram	< 2s	> 5s
AI rewrite throughput	Counter	Stable	Drop > 30%

Instrumentation

async function trackGrammarlyCall(api: 'score' | 'ai' | 'plagiarism', textLen: number, fn: () => Promise<any>) {
  const start = Date.now();
  try {
    const result = await fn();
    metrics.histogram('grammarly.api.latency', Date.now() - start, { api });
    metrics.increment('grammarly.api.calls', { api });
    metrics.gauge('grammarly.text.length', textLen, { api });
    return result;
  } catch (err) {
    metrics.increment('grammarly.api.errors', { api, status: err.status });
    throw err;
  }
}

Health Check Dashboard

async function grammarlyHealth(): Promise<Record<string, string>> {
  const latencyP95 = await metrics.query('grammarly.api.latency', 'p95', '5m');
  const errorRate = await metrics.query('grammarly.api.error_rate', 'avg', '5m');
  const quotaUsed = await grammarlyAdmin.getQuotaUsage();
  return {
    api_latency: latencyP95 < 300 ? 'healthy' : 'slow',
    error_rate: errorRate < 0.01 ? 'healthy' : 'degraded',
    quota: quotaUsed < 0.8 ? 'healthy' : 'at_risk',
  };
}

Alerting Rules

const alerts = [
  { metric: 'grammarly.api.latency_p95', condition: '> 800ms', window: '10m', severity: 'warning' },
  { metric: 'grammarly.api.error_rate', condition: '> 0.05', window: '5m', severity: 'critical' },
  { metric: 'grammarly.quota.daily_pct', condition: '> 0.90', window: '1h', severity: 'warning' },
  { metric: 'grammarly.ai.throughput', condition: 'drop > 30%', window: '15m', severity: 'critical' },
];

Structured Logging

function logGrammarlyEvent(api: string, data: Record<string, any>) {
  console.log(JSON.stringify({
    service: 'grammarly', api,
    duration_ms: data.latency, status: data.status,
    text_length: data.textLen, suggestion_count: data.suggestions,
    // Never log user text content — only metadata
    timestamp: new Date().toISOString(),
  }));
}

Error Handling

Signal	Meaning	Action
429 rate limit	Token quota exhausted	Back off, check daily usage, request limit increase
Latency spike on /score	Grammarly service degradation	Check status page, enable local cache fallback
Suggestion count drops to 0	API schema change or auth failure	Verify API key, check response format
Plagiarism timeout > 5s	Large document or service overload	Chunk text, retry with exponential backoff

Resources

• Grammarly Developer Portal

Next Steps

See grammarly-incident-runbook.