エージェントが壊れる10パターン：ログから作る“失敗分類”辞典

{
  "trace_id": "f01-001",
  "event": "plan_generated",
  "goal": "売上レポートを作成して",
  "generated_plan": [
    "過去5年分の売上データを全データソースから取得",
    "競合3社の売上データをWebスクレイピングで収集",
    "機械学習モデルで来期予測を生成",
    "取締役会向けプレゼン資料を40ページで作成",
    "関係者15名にメール送信"
  ],
  "expected_plan": ["当月売上データ取得", "集計", "レポート生成"],
  "warning": "サブタスク数が想定の5倍"
}

{
  "trace_id": "f01-002",
  "event": "plan_conflict_detected",
  "goal": "コスト削減と品質向上を同時に実現して",
  "subgoals": [
    {"id": "sg1", "action": "外注先を最安ベンダーに切り替え"},
    {"id": "sg2", "action": "品質基準を現行の2倍に引き上げ"},
    {"id": "sg3", "action": "テスト工程を50%削減してコスト削減"}
  ],
  "conflict": "sg2とsg3が矛盾: 品質向上とテスト削減は両立不可",
  "resolution": "none"
}

{
  "trace_id": "f01-003",
  "event": "assumption_mismatch",
  "goal": "顧客データをクリーニングして",
  "agent_assumption": "全カラムのNULL値を0で埋める",
  "user_expectation": "住所カラムのみ正規化する",
  "result": "数値カラム2,847件が0で上書きされた",
  "reversible": false
}

{
  "trace_id": "f01-004",
  "event": "error_amplification",
  "step_1": {"action": "市場規模を推定", "error": "単位を百万円→億円と誤認"},
  "step_2": {"action": "市場シェアを計算", "error": "10倍の市場規模で計算"},
  "step_3": {"action": "投資計画を策定", "error": "10倍の売上予測で投資額を算出"},
  "final_output": "投資額が適正値の10倍で提案された",
  "root_cause": "step_1の単位誤認が下流で増幅"
}

{
  "trace_id": "f02-001",
  "event": "tool_call_failed",
  "tool": "crm_api.update_customer",
  "parameters": {
    "customer_id": "not-a-number",
    "email": 12345,
    "phone": {"nested": "object"}
  },
  "schema_errors": [
    "customer_id: expected integer, got string",
    "email: expected string, got number",
    "phone: expected string, got object"
  ],
  "status": "blocked_by_validation"
}

{
  "trace_id": "f02-002",
  "event": "tool_not_found",
  "requested_tool": "database.execute_raw_sql",
  "available_tools": [
    "database.query_readonly",
    "database.get_schema",
    "database.list_tables"
  ],
  "llm_reasoning": "SQLを直接実行すれば効率的だと判断",
  "status": "tool_not_found_error"
}

{
  "trace_id": "f02-003",
  "event": "partial_response_ignored",
  "tool": "search_api.search",
  "response": {
    "status": 200,
    "results": [{"id": 1, "title": "Result A"}],
    "pagination": {"total": 150, "page": 1, "per_page": 10},
    "has_more": true
  },
  "agent_action": "10件の結果のみで分析を完了",
  "missed_results": 140
}

{
  "trace_id": "f02-004",
  "event": "side_effect_no_rollback",
  "tool_chain": [
    {"tool": "payment.charge", "status": "success", "amount": 50000},
    {"tool": "inventory.reserve", "status": "success", "items": 3},
    {"tool": "shipping.create_order", "status": "failed", "error": "address_invalid"}
  ],
  "rollback_attempted": false,
  "impact": "課金と在庫確保は完了したが配送注文が失敗。不整合状態"
}

// エージェントの出力（壊れたJSON）
{"result": "分析完了", "metrics": {"accuracy": 0.95, "recall": 0.87,
ここで追加の説明を加えます。精度は非常に高く...
"precision": 0.91}}
 
// パーサーのエラー
SyntaxError: Unexpected token 'こ' at position 67

{
  "trace_id": "f03-002",
  "event": "schema_validation_failed",
  "expected_schema": ["id", "title", "category", "priority", "assignee"],
  "actual_output": {
    "id": "TICKET-1234",
    "title": "ログインエラーの調査",
    "category": "バグ"
  },
  "missing_fields": ["priority", "assignee"],
  "downstream_error": "priority is required for SLA calculation"
}

{
  "trace_id": "f03-003",
  "event": "type_mismatch",
  "field": "price",
  "expected_type": "number",
  "actual_value": "1,234円",
  "actual_type": "string",
  "downstream_error": "Cannot perform arithmetic on string '1,234円'",
  "other_mismatches": [
    {"field": "in_stock", "expected": "boolean", "actual": "はい"},
    {"field": "quantity", "expected": "integer", "actual": "3.0"}
  ]
}

{
  "trace_id": "f04-001",
  "event": "infinite_loop_detected",
  "iterations": [
    {"step": 1, "action": "レポート生成", "eval": "品質不十分、再生成"},
    {"step": 2, "action": "レポート再生成", "eval": "まだ改善の余地あり、再生成"},
    {"step": 3, "action": "レポート再生成", "eval": "さらに改善可能、再生成"},
    {"step": 12, "action": "レポート再生成", "eval": "まだ完璧ではない、再生成"}
  ],
  "tokens_consumed": 184500,
  "max_iterations_setting": "none",
  "terminated_by": "token_budget_exceeded"
}

{
  "trace_id": "f04-002",
  "event": "delegation_deadlock",
  "agents": ["planner", "executor", "reviewer"],
  "cycle": [
    {"from": "planner", "to": "executor", "reason": "実行情報が不足、先にデータ確認を"},
    {"from": "executor", "to": "reviewer", "reason": "実行前にレビューが必要"},
    {"from": "reviewer", "to": "planner", "reason": "計画が未確定のためレビュー不可"},
    {"from": "planner", "to": "executor", "reason": "実行情報が不足、先にデータ確認を"}
  ],
  "cycle_count": 8,
  "resolution": "none"
}

{
  "trace_id": "f04-003",
  "event": "retry_storm",
  "tool": "llm_api.generate",
  "retry_history": [
    {"attempt": 1, "error": "rate_limited", "wait": "1s"},
    {"attempt": 2, "error": "rate_limited", "wait": "1s"},
    {"attempt": 3, "error": "rate_limited", "wait": "1s"},
    {"attempt": 50, "error": "rate_limited", "wait": "1s"}
  ],
  "total_attempts": 50,
  "backoff_strategy": "none",
  "cost_impact": "$47.20 (想定の15倍)"
}

{
  "trace_id": "f05-001",
  "event": "context_overflow",
  "model": "gpt-4o",
  "context_tokens": 127800,
  "max_tokens": 128000,
  "truncated_content": [
    "初回の目標定義（重要）",
    "ステップ1-3の実行結果",
    "ユーザーの追加指示2件"
  ],
  "retained_content": "直近の会話3ターンのみ",
  "impact": "初回の目標を忘れ、関係ない話題について回答"
}

{
  "trace_id": "f05-002",
  "event": "context_cost_explosion",
  "architecture": "multi_agent",
  "agents": ["planner", "researcher", "writer"],
  "shared_context_tokens": 95000,
  "per_agent_cost": {
    "planner": "$0.285",
    "researcher": "$0.285",
    "writer": "$0.285"
  },
  "total_cost_per_turn": "$0.855",
  "optimized_cost": "$0.190 (独立コンテキスト)",
  "waste_ratio": "4.5x"
}

{
  "trace_id": "f05-003",
  "event": "context_drift",
  "initial_goal": "Q4の売上分析レポートを作成",
  "turn_5_topic": "Q4売上の地域別分析",
  "turn_10_topic": "地域別の人口統計データ",
  "turn_15_topic": "日本の人口動態トレンド",
  "turn_20_topic": "少子高齢化の社会的影響",
  "drift_score": 0.23,
  "original_goal_relevance": "低"
}

{
  "trace_id": "f06-001",
  "event": "hallucinated_citation",
  "output": "Gartnerの2025年レポート(Report ID: GT-2025-AI-0847)によると、AIエージェント導入企業の92%が...",
  "verification": {
    "report_id_exists": false,
    "statistic_source_found": false,
    "closest_real_stat": "PwC調査: 79%が導入済み"
  },
  "confidence_score": 0.94,
  "impact": "架空の統計に基づいた経営判断の提案"
}

{
  "trace_id": "f06-002",
  "event": "numerical_hallucination",
  "task": "競合A社の売上を分析",
  "output": {
    "revenue_2025": "4,280億円",
    "yoy_growth": "23.5%",
    "market_share": "34.2%"
  },
  "ground_truth": {
    "revenue_2025": "2,150億円",
    "yoy_growth": "8.1%",
    "market_share": "18.7%"
  },
  "error_magnitude": "売上2倍、成長率3倍、シェア2倍の過大評価"
}

{
  "trace_id": "f06-003",
  "event": "false_completion_claim",
  "task": "顧客リスト500件にメール送信",
  "agent_response": "500件のメール送信が完了しました。開封率は32%です。",
  "actual_execution_log": {
    "emails_sent": 0,
    "tool_calls": [],
    "mail_api_invoked": false
  },
  "discrepancy": "ツール呼び出しログが空。実際には何も実行されていない"
}

{
  "trace_id": "f07-001",
  "event": "rate_limit_ignored",
  "tool": "openai_api.chat_completion",
  "response": {
    "status": 429,
    "headers": {
      "x-ratelimit-remaining": "0",
      "x-ratelimit-reset": "1708520400",
      "retry-after": "60"
    }
  },
  "agent_action": "即座にリトライ（retry-afterヘッダを無視）",
  "consequence": "アカウント一時停止（15分間）"
}

{
  "trace_id": "f07-002",
  "event": "cascade_timeout",
  "chain": [
    {"tool": "search_api", "timeout": "30s", "actual": "28s", "status": "success"},
    {"tool": "llm_api.summarize", "timeout": "30s", "actual": "30s", "status": "timeout"},
    {"tool": "db.save_result", "timeout": "10s", "actual": "skipped", "status": "not_executed"}
  ],
  "total_elapsed": "58s",
  "user_timeout": "30s",
  "impact": "ユーザーには30秒でタイムアウトだが、内部では58秒消費"
}

{
  "trace_id": "f07-003",
  "event": "zombie_process",
  "tool": "code_executor.run_script",
  "timeout_at": "2026-02-21T10:05:00Z",
  "process_status_at_10_05": "timeout_reported_to_agent",
  "process_status_at_10_15": "still_running",
  "process_status_at_10_30": "still_running",
  "resource_consumption": {
    "cpu": "95%",
    "memory": "2.1GB"
  },
  "impact": "タイムアウト後もプロセスがリソースを消費し続ける"
}

{
  "trace_id": "f08-001",
  "event": "privilege_escalation",
  "initial_permission": "read_only",
  "tool_chain": [
    {"tool": "db.query", "permission": "read", "status": "success"},
    {"tool": "db.query", "query": "SELECT * FROM admin_config", "status": "success"},
    {"tool": "api.update_config", "permission": "write", "data": "admin_configの値を使用"}
  ],
  "escalation_path": "読み取り専用ユーザーがadmin設定を読み取り、その値で書き込みAPIを呼び出し",
  "policy_violation": "最小権限の原則に違反"
}

{
  "trace_id": "f08-002",
  "event": "cross_tenant_access",
  "agent_tenant": "company_a",
  "query": "SELECT * FROM customers WHERE region = 'Tokyo'",
  "result_tenants": ["company_a", "company_b", "company_c"],
  "leaked_records": 847,
  "root_cause": "WHERE句にtenant_idフィルタが欠落",
  "detection": "監査ログの事後レビューで発見"
}

{
  "trace_id": "f08-003",
  "event": "api_key_exposure",
  "agent_output": "データベースに接続しました。使用した接続文字列: postgresql://admin:S3cretPass@db.example.com:5432/prod",
  "exposed_credentials": [
    {"type": "db_password", "value": "S3cretPass"},
    {"type": "db_host", "value": "db.example.com"}
  ],
  "output_destination": "ユーザー向けチャットUI",
  "impact": "本番DBの認証情報がエンドユーザーに露出"
}

{
  "trace_id": "f09-001",
  "event": "memory_corruption",
  "memory_store": "vector_db",
  "corrupted_entry": {
    "id": "mem-4521",
    "content": "顧客Aの契約額は月額50万円",
    "stored_at": "2026-01-15",
    "source": "hallucinated_output"
  },
  "actual_contract": "月額30万円",
  "impact": "以降の全会話で誤った契約額を参照",
  "contamination_radius": "47件の後続応答に影響"
}

{
  "trace_id": "f09-002",
  "event": "session_state_inconsistency",
  "session_1": {
    "user_preference": "日本語で応答",
    "task_context": "Q4レポート作成中",
    "progress": "データ収集完了、分析中"
  },
  "session_2_restored": {
    "user_preference": "missing",
    "task_context": "missing",
    "progress": "missing"
  },
  "agent_response": "Hello! How can I help you today?",
  "impact": "前回セッションの作業が全て失われ、最初からやり直し"
}

{
  "trace_id": "f10-001",
  "event": "message_format_mismatch",
  "sender": "research_agent",
  "receiver": "writer_agent",
  "sent_message": {
    "format": "markdown",
    "content": "## 調査結果\n- 市場規模: 1.2兆円\n- 成長率: 15%"
  },
  "receiver_expected": {
    "format": "json",
    "schema": {"market_size": "number", "growth_rate": "number"}
  },
  "parse_error": "JSON.parse failed: Unexpected token '#'",
  "impact": "Writer Agentが調査結果を読み取れず、空のレポートを生成"
}

{
  "trace_id": "f10-002",
  "event": "responsibility_gap",
  "task": "顧客からのクレーム対応",
  "agents": {
    "classifier": {"role": "問い合わせ分類", "handled": true},
    "responder": {"role": "定型回答の生成", "handled": true},
    "escalator": {"role": "上位者へのエスカレーション", "handled": false}
  },
  "gap": "クレームが「重大」に分類されたが、エスカレーション担当が未定義",
  "result": "重大クレームが24時間放置された",
  "sla_violation": true
}

{
  "trace_id": "一意のトレースID",
  "timestamp": "ISO 8601形式",
  "failure_category": "F01-F10",
  "severity": "low | medium | high | critical",
  "event": "イベント名",
  "agent_id": "エージェントID",
  "tool": "関連ツール名（該当する場合）",
  "input_summary": "入力の要約",
  "output_summary": "出力の要約",
  "expected_behavior": "期待された挙動",
  "actual_behavior": "実際の挙動",
  "root_cause": "根本原因",
  "resolution": "対応内容",
  "prevention": "再発防止策",
  "related_traces": ["関連するトレースIDのリスト"]
}