This prompt is designed for support engineering and SRE teams who need to impose a consistent, structured taxonomy on a high volume of production error instances. The core job-to-be-done is transforming raw, unstructured error payloads—such as stack traces, log lines, or API error bodies—into a standardized root cause category with a calibrated confidence score. The ideal user is an engineer building an internal triage dashboard, automating runbook routing, or enriching incident alerts before they reach an on-call rotation. The required context is the raw error text itself; the prompt is engineered to work with the information present in the error payload and does not require deep system internals knowledge to be injected at runtime.
Prompt
Common Cause Classification Prompt for Error Codes

When to Use This Prompt
Defines the ideal production scenario, required inputs, and critical limitations for the Common Cause Classification Prompt.
Use this prompt when you need to batch-process error logs to identify systemic failure patterns or when you are building a feedback loop from production errors back to your runbook library. It is particularly effective for handling ambiguous or multi-cause errors because it is instructed to surface uncertainty and propose multiple potential categories rather than forcing a single, potentially incorrect label. For example, a ConnectionTimeout error could stem from a network partition or an overloaded database; this prompt will output both possibilities with distinct confidence scores, allowing a downstream system or human reviewer to make the final determination. The output is a structured JSON object that includes the primary classification, alternative classifications, and a confidence score, making it directly ingestible by automated workflows.
Do not use this prompt for real-time incident response where latency is critical, as the model's inference time may introduce unacceptable delays in an active firefight. It is also unsuitable for errors where the root cause requires deep system internals knowledge not present in the error payload itself, such as a memory corruption bug that manifests as a generic segmentation fault. In such cases, the prompt will correctly identify the symptom but cannot infer the underlying cause without additional context. The next step after reading this section is to review the prompt template and understand how to adapt its input variables to your specific error format.
Use Case Fit
Where the Common Cause Classification Prompt delivers reliable value and where it introduces operational risk. Use these cards to decide if this prompt fits your production workflow.
Good Fit: High-Volume Triage
Use when: Support engineers face hundreds of error instances daily and need consistent, fast categorization to feed dashboards and runbooks. Why: The prompt scales classification without manual review of every instance, reducing mean time to triage.
Bad Fit: Novel or Zero-Day Errors
Avoid when: The error has never been seen before and no runbook or historical pattern exists. Risk: The model may force a novel error into an existing category with high confidence, masking a new failure mode. Guardrail: Require a confidence floor and route low-confidence predictions to a human-staged 'unclassified' queue.
Required Inputs
Prerequisites: A structured error log containing the error code, raw message, stack trace, and service context. Why: The prompt needs more than an error code string. Without the message and service name, classification accuracy degrades significantly. Guardrail: Validate input completeness before calling the model; reject or flag instances missing required fields.
Operational Risk: Taxonomy Drift
What to watch: The predefined taxonomy becomes stale as new services and failure modes are deployed. Risk: The model continues classifying into outdated categories, producing misleading dashboards. Guardrail: Version your taxonomy alongside your service catalog. Run a weekly audit comparing 'unclassified' cluster sizes against recent deployments.
Operational Risk: Multi-Cause Ambiguity
What to watch: A single error instance results from multiple root causes (e.g., a timeout caused by a network partition exacerbated by a missing circuit breaker). Risk: The model picks one cause and ignores the other, leading to incomplete remediation. Guardrail: Prompt the model to output a primary cause and a list of contributing factors. If the primary confidence is below a threshold, flag for human review.
Operational Risk: Hallucinated Causes
What to watch: The model invents a plausible-sounding but incorrect root cause, especially for vague error messages like 'Internal Server Error'. Risk: Operators waste time investigating a fictional failure mode. Guardrail: Require the model to cite specific evidence from the input log lines for its classification. Implement an automated check that verifies the cited evidence exists in the input.
Copy-Ready Prompt Template
A ready-to-use prompt for classifying error instances into root cause categories with confidence scores.
This prompt template is designed to be pasted directly into your AI orchestration layer. It instructs the model to act as a support engineer classifying production errors at scale. The model will analyze an error instance, map it to a predefined taxonomy, and return a structured classification with a confidence score and supporting rationale. Before using this template, ensure you have a well-defined error taxonomy and a set of representative examples for few-shot learning, which will significantly improve classification consistency.
codeSYSTEM: You are a senior support engineer specializing in production error analysis. Your task is to classify a given error instance into a root cause category from a predefined taxonomy. You must provide a confidence score and a concise rationale for your classification. If the error is ambiguous or could belong to multiple categories, list the alternatives with their respective confidence scores and explain the ambiguity. USER: Classify the following error instance using the provided taxonomy and examples. ## Error Taxonomy [TAXONOMY] ## Few-Shot Examples [EXAMPLES] ## Error Instance to Classify Error Code: [ERROR_CODE] Error Message: [ERROR_MESSAGE] Stack Trace / Context: [ERROR_CONTEXT] Service: [SERVICE_NAME] ## Output Schema Return a valid JSON object with the following structure: { "primary_classification": { "category": "string", "confidence": 0.0-1.0, "rationale": "string" }, "alternative_classifications": [ { "category": "string", "confidence": 0.0-1.0, "rationale": "string" } ], "is_ambiguous": true/false, "ambiguity_note": "string or null" } ## Constraints - Only use categories from the provided taxonomy. - If confidence is below 0.7, you MUST provide at least one alternative classification. - The rationale must reference specific details from the error instance (e.g., error code, message text, stack trace). - Do not invent categories or make assumptions about the system not present in the input.
To adapt this template, replace the square-bracket placeholders with live data. [TAXONOMY] should be a structured list of your error categories, such as 'Network Timeout', 'Invalid Input', 'Dependency Failure', or 'Internal Server Error'. [EXAMPLES] should contain 3-5 few-shot examples showing an error instance and its correct JSON classification. This is critical for teaching the model the boundaries of your taxonomy. The remaining placeholders ([ERROR_CODE], [ERROR_MESSAGE], etc.) should be populated from your error reporting system for each classification call. For high-stakes environments, consider adding a [RISK_LEVEL] constraint that forces a human review flag for low-confidence or ambiguous classifications.
After pasting this prompt into your orchestration layer, you must implement a validation step. The model's JSON output should be parsed and validated against the expected schema. Any output that fails to parse or is missing required fields should trigger a retry or fallback logic. For ambiguous cases where is_ambiguous is true, route the error instance to a human review queue. This ensures that your runbooks and dashboards are fed with high-confidence data, while edge cases are handled with the necessary human judgment.
Prompt Variables
Every placeholder the Common Cause Classification Prompt expects, with validation notes to ensure reliable classification at scale.
| Placeholder | Purpose | Example | Validation Notes |
|---|---|---|---|
[ERROR_INSTANCE] | The raw error payload to classify, including status code, error body, and headers | {"status": 429, "body": {"error": "rate_limit_exceeded"}, "headers": {"Retry-After": "30"}} | Must be valid JSON string. Parse check before prompt assembly. Reject empty or null payloads. |
[ERROR_TAXONOMY] | The predefined hierarchy of error categories and subcategories to map against | {"categories": [{"id": "rate_limit", "name": "Rate Limiting", "subcategories": ["quota_exceeded", "burst_throttle"]}]} | Must be valid JSON with at least one category. Schema check: categories array required, each with id and name fields. |
[CLASSIFICATION_SCHEMA] | The output structure the model must produce for each classification | {"category_id": "string", "confidence": 0.0-1.0, "evidence_fields": ["string"], "alternative_categories": [{"id": "string", "confidence": 0.0-1.0}]} | Must be valid JSON schema. Include required fields: category_id, confidence, evidence_fields. Confidence must be constrained to 0.0-1.0 range. |
[AMBIGUITY_THRESHOLD] | Confidence score below which the model must flag the classification as ambiguous | 0.65 | Must be a float between 0.0 and 1.0. Default 0.7 if not provided. Lower values increase multi-category outputs. |
[MAX_ALTERNATIVES] | Maximum number of alternative categories to return when confidence is below threshold | 3 | Must be a positive integer. Default 2 if not provided. Set to 0 to disable alternative classification. |
[CONTEXT_WINDOW] | Additional context about the system state when the error occurred, such as recent deployments or traffic patterns | "Deployed v2.3.1 to canary 5 minutes before spike. Traffic 3x normal." | Optional string. Null allowed. If provided, must be under 2000 characters to avoid diluting error signal. Truncate with warning if exceeded. |
[PREVIOUS_CLASSIFICATIONS] | Historical classifications for the same or similar error instances to improve consistency | [{"error_signature": "429_rate_limit", "category_id": "rate_limit", "count": 47}] | Optional array. Null allowed. If provided, each entry must have error_signature and category_id fields. Used for consistency checks, not as ground truth. |
Implementation Harness Notes
How to wire the Common Cause Classification Prompt into a production classification pipeline.
This prompt is designed to be a single step within a larger error processing pipeline, not a standalone chatbot. The implementation harness must treat the model call as a deterministic classifier with a structured output contract. The primary integration point is an event-driven function that receives a batch of error instances, enriches them with relevant context (stack traces, timestamps, service names), and calls the LLM to produce a normalized classification payload. The harness is responsible for enforcing the [OUTPUT_SCHEMA], handling model refusals or malformed JSON, and routing low-confidence classifications to a human review queue.
Start by wrapping the prompt in a function that accepts a list of error objects and returns a list of classification results. Before calling the model, validate that each error object contains the required fields: error_code, error_message, and service_name. Strip any sensitive data (PII, secrets, internal IPs) using a redaction step before the prompt is assembled. Use a model with strong JSON mode support (e.g., GPT-4o, Claude 3.5 Sonnet) and set response_format to json_schema with the exact classification schema. Implement a retry loop with exponential backoff (max 3 attempts) that catches json.JSONDecodeError and schema validation failures. On the second retry, append the validation error to the prompt as additional context: "The previous output failed validation: [ERROR]. Please correct the JSON." If all retries fail, log the raw output and route the error instance to a dead-letter queue for manual triage.
For production observability, log every classification call with: the model version, prompt template hash, input error code, output root cause category, confidence score, and latency. Use these logs to build a dashboard that tracks classification consistency over time. Run a weekly eval job that samples 100 classified errors and has a senior engineer review them against a golden dataset. If agreement drops below 90%, trigger a prompt review cycle. The most common failure mode is ambiguous errors that span multiple categories—the harness should flag any classification with a confidence score below 0.7 for human review. Do not auto-close incidents based solely on LLM classifications without a human-in-the-loop checkpoint for high-severity errors.
Expected Output Contract
Defines the exact fields, types, and validation rules for the structured JSON output produced by the Common Cause Classification Prompt. Use this contract to build a parser that validates the model's response before it enters your runbook or dashboard system.
| Field or Element | Type or Format | Required | Validation Rule |
|---|---|---|---|
classification_id | string (UUID v4) | Must match regex for UUID v4. Reject if missing or malformed. | |
error_instance_ref | string | Must be a non-empty string matching the [ERROR_INSTANCE_ID] from the input. Reject if null or empty. | |
primary_category | string | Must exactly match one of the labels in [TAXONOMY_CATEGORIES]. Reject if not in the allowed set. | |
confidence_score | number (float) | Must be a float between 0.0 and 1.0 inclusive. Reject if outside range or not a number. | |
alternative_categories | array of objects | If present, each object must have 'category' (string in [TAXONOMY_CATEGORIES]) and 'confidence' (float 0.0-1.0). Reject if schema is violated. | |
rationale_summary | string | Must be a non-empty string between 20 and 500 characters. Reject if outside length bounds. | |
requires_human_review | boolean | Must be true if confidence_score < [CONFIDENCE_THRESHOLD] or if primary_category is in [HIGH_RISK_CATEGORIES]. Reject if type is not boolean. | |
classification_timestamp | string (ISO 8601) | Must be a valid ISO 8601 datetime string in UTC. Reject if unparseable or missing timezone offset. |
Common Failure Modes
When classifying error codes into root cause categories at scale, these are the most common failure patterns that degrade accuracy, consistency, and operational usefulness. Each card identifies a specific failure mode and the guardrail that prevents it from reaching production dashboards or runbooks.
Ambiguous Error Collapse
What to watch: The model collapses multiple distinct root causes into a single catch-all category like 'Internal Server Error' or 'Unknown' when confidence is low, losing signal for downstream runbooks. This happens most often with sparse error bodies or generic HTTP 500 responses. Guardrail: Require the prompt to output a confidence_score per classification and set a minimum threshold. When confidence falls below the threshold, route to an 'Unclassified-NeedsReview' bucket instead of forcing a best-guess category. Add few-shot examples showing how to distinguish similar error signatures.
Multi-Cause Flattening
What to watch: A single error instance has multiple contributing root causes (e.g., a timeout caused by both a slow downstream service and an undersized connection pool), but the prompt forces a single-category output. The secondary cause is lost, and the runbook only addresses the primary cause, leaving the underlying issue unresolved. Guardrail: Allow the output schema to include an array of contributing_causes with individual confidence scores, not just a single primary_cause. Validate that multi-cause outputs appear in production traces where error context contains multiple failure signals.
Taxonomy Drift Over Time
What to watch: The classification taxonomy defined in the system prompt becomes stale as new error codes, services, or failure patterns emerge. The model starts forcing new errors into old categories or invents ad-hoc categories that don't match the runbook mapping, breaking downstream dashboards and alerting rules. Guardrail: Version the taxonomy in the prompt with a taxonomy_version field. Run a weekly audit prompt that compares unclassified or low-confidence error instances against the current taxonomy and flags gaps. Require human review before adding new categories to prevent taxonomy sprawl.
Context Window Truncation
What to watch: Long error traces, stack traces, or multi-service log contexts exceed the model's context window. The prompt silently truncates the input, and the model classifies based on only the first portion of the error, missing the root cause buried deeper in the trace. Guardrail: Implement a pre-processing step that extracts the most relevant error segments before classification. Use a summarization pass on long stack traces to preserve exception types, failing service names, and causal chains. Add a context_completeness flag to the output indicating whether the full error context was available during classification.
Overconfident Hallucination on Novel Errors
What to watch: The model encounters an entirely new error pattern not represented in few-shot examples or taxonomy descriptions. Instead of expressing uncertainty, it confidently maps the novel error to a semantically similar but incorrect existing category, producing a false match that misdirects the on-call engineer. Guardrail: Include negative examples in the prompt showing when to abstain. Add a novelty_flag boolean to the output schema. Run periodic eval suites with synthetic novel errors to measure the abstention rate. If the model classifies a known-novel error with high confidence, the prompt needs more refusal training examples.
Runbook Mismatch After Reclassification
What to watch: The classification output feeds directly into automated runbook selection or alert routing. When the model reclassifies an error that previously mapped to a different category, the wrong runbook executes, potentially running destructive diagnostic commands or paging the wrong team. Guardrail: Implement a stability check before automated action. Compare the new classification against the last N classifications for the same error signature. If the category changed, route to human review instead of executing the runbook automatically. Log all reclassification events for audit and prompt improvement cycles.
Evaluation Rubric
Use this rubric to test classification quality before shipping the Common Cause Classification Prompt to production. Each criterion targets a specific failure mode observed in error code classification systems.
| Criterion | Pass Standard | Failure Signal | Test Method |
|---|---|---|---|
Classification Consistency | Same error instance with minor text variations receives identical root cause category across 5 repeated runs | Category flips between runs for the same error when only timestamp or UUID changes | Run 5 identical error payloads with varying timestamps; require 100% category agreement |
Confidence Score Calibration | Confidence scores above 0.85 correspond to >= 90% human-agreement rate on a 50-sample golden set | High-confidence predictions (above 0.90) are overturned by human reviewers more than 15% of the time | Compare model confidence scores against 3 human annotator majority-vote labels on golden dataset |
Ambiguous Error Handling | Errors with multiple plausible causes produce a primary category plus at least one alternative with confidence scores, or return | Multi-cause errors are forced into a single category with high confidence and no alternatives listed | Feed 10 constructed multi-cause error scenarios; verify alternatives array is non-empty or needs_human_review is true |
Unknown Error Degradation | Errors with no clear match to the taxonomy return category | Novel or out-of-distribution errors are confidently misclassified into an existing category | Feed 5 error messages from a different service or fabricated patterns; verify unclassified output and low confidence |
Taxonomy Boundary Adherence | Classification output uses only categories from the provided [TAXONOMY] list; no invented or merged categories | Output contains a category string not present in the input taxonomy, or concatenates two taxonomy entries | Parse output category field; assert membership in the provided taxonomy set using exact string match |
Field Completeness | Every required output field is present and non-null: category, confidence, evidence_snippet, alternatives, needs_human_review | Missing alternatives array, null confidence, or empty evidence_snippet on a classified error | Schema-validate output against the [OUTPUT_SCHEMA]; reject any response missing required fields |
Evidence Grounding | The evidence_snippet field contains a verbatim substring from the input error message that supports the classification | Evidence snippet is hallucinated, paraphrased, or references details not present in the input error payload | Check that evidence_snippet is a substring of the input error text using string containment; flag if not found |
Latency Budget Compliance | Classification completes within [MAX_LATENCY_MS] milliseconds for 95th percentile across 100 requests | P95 latency exceeds budget by more than 20% under steady load | Load test with 100 concurrent requests; measure P95 response time and compare against threshold |
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Give teams answers from docs, tickets, runbooks, and product data with sources and permissions.
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Adapt This Prompt
How to adapt
Use the base prompt with a frontier model and a small sample of error logs. Remove strict output schema requirements initially; accept a markdown table or bulleted list. Focus on getting reasonable category labels and confidence scores for 20–50 error instances before hardening the format.
Watch for
- Category label drift across runs (same error getting different labels)
- Confidence scores that are always 0.9+ without justification
- Multi-cause errors being forced into a single category
- No handling for errors missing stack traces or context fields

About the author
Prasad Kumkar
CEO & MD, Inference Systems
Prasad Kumkar is the CEO & MD of Inference Systems and writes about AI systems architecture, LLM infrastructure, model serving, evaluation, and production deployment. Over 5+ years, he has worked across computer vision models, L5 autonomous vehicle systems, and LLM research, with a focus on taking complex AI ideas into real-world engineering systems.
His work and writing cover AI systems, large language models, AI agents, multimodal systems, autonomous systems, inference optimization, RAG, evaluation, and production AI engineering.
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