Monitoring & Observability

Monitor your LangGraph Platform deployments with LangSmith

Overview

LangGraph Platform deployments automatically integrate with LangSmith for comprehensive observability. Every request is traced with full LLM details.

Built-in Tracing: No configuration needed - all deployments are automatically traced in LangSmith.

Viewing Traces

1. Access LangSmith

   Go to smith.langchain.com

2. Select Project

   Choose your project (e.g., “mcp-server-langgraph”)

3. View Traces

   See all requests with:

   • Full prompts and completions
   • Token usage and costs
   • Latency breakdown
   • Error details

What’s Captured

Every trace includes:

LLM Calls

• Full prompts sent to LLM
• Complete model responses
• Token counts (input/output)
• Model parameters
• Latency per call

Agent Steps

• Routing decisions
• Tool invocations
• State transitions
• Conditional flows
• Execution order

Metadata

• User ID and session ID
• Request timestamp
• Environment (prod/staging)
• Custom tags
• Deployment version

Errors

• Full stack traces
• Input that caused error
• Error context
• Failure timing
• Retry attempts

Metrics Dashboard

View key metrics in LangSmith:

Request Volume

• Total invocations over time
• Requests per second
• Peak traffic periods

Latency

• P50 Latency: Median response time
• P95 Latency: 95th percentile
• P99 Latency: 99th percentile
• Max Latency: Slowest requests

Success Rate

• Successful requests (200 OK)
• Failed requests (4xx, 5xx)
• Error rate percentage
• Error types breakdown

Token Usage

• Total tokens consumed
• Input vs output tokens
• Tokens per request
• Token usage trends

Cost Tracking

• Estimated costs by model
• Cost per user/session
• Daily/monthly spend
• Cost breakdown by feature

Filtering Traces

By Status

status:error
status:success

By Latency

latency > 5s
latency < 1s

By User

metadata.user_id:"[e-mail]"

By Tags

tags:"production"
tags:"high-priority"

By Date

timestamp > 2025-10-01
timestamp < 2025-10-10

Debugging Workflow

1. Find Failing Traces

   Filter by status:error and sort by timestamp descending

2. Analyze Error

   Click on trace to see:

   • Exact input that caused failure
   • Full Python stack trace
   • All steps before error
   • Timing information
3. Compare with Success

   Find similar successful trace and compare side-by-side

4. Fix and Redeploy

   Fix issue in code and redeploy:

   langgraph deploy
   

5. Verify Fix

   Monitor new traces to confirm error is resolved

Performance Optimization

Identify Slow Traces

1. Filter: latency > 5s
2. Sort by latency descending
3. Expand trace to see timing breakdown
4. Identify bottlenecks:
   • Slow LLM calls → Try faster model
   • Slow tool calls → Add caching
   • Redundant calls → Optimize logic

Example Optimization

Before: 8.5s total latency

• LLM call 1: 3.2s
• Tool call: 2.1s
• LLM call 2: 3.2s

Optimization: Add caching to tool call

After: 4.5s total latency

• LLM call 1: 3.2s
• Tool call (cached): 0.1s
• LLM call 2: 1.2s (smaller context)

Alerts

Set up alerts in LangSmith:

1. Go to Project Settings

   Navigate to Settings → Alerts

2. Create Alert Rule

   Configure alert conditions:

   • High Error Rate: Error rate > 5%
   • High Latency: P95 > 5 seconds
   • Budget Exceeded: Daily cost > $50
3. Configure Notifications

   Choose notification channels:

   • Email
   • Slack
   • Webhook
   • PagerDuty

Custom Metadata

Add custom metadata to traces for better filtering:

from langchain_core.runnables import RunnableConfig

config = RunnableConfig(
    tags=["premium-user", "high-priority"],
    metadata={
        "user_id": "[e-mail]",
        "session_id": "sess_abc123",
        "feature": "analysis",
        "cost_center": "sales"
    }
)

result = await graph.ainvoke(input, config=config)

Now filter in LangSmith:

• tags:"premium-user"
• metadata.cost_center:"sales"
• metadata.feature:"analysis"

Datasets & Evaluation

Create Dataset from Production

1. Filter Successful Traces

   Filter: status:success AND tags:"production"

2. Select Examples

   Choose representative traces (varied inputs/outputs)

3. Add to Dataset

   Click “Add to Dataset” → Name it “prod-examples-oct-2025”

Run Evaluation

Compare model performance:

from langsmith import Client

client = Client()

## Test on production dataset
results = client.run_on_dataset(
    dataset_name="prod-examples-oct-2025",
    llm_or_chain_factory=lambda: graph,
    project_name="eval-claude-vs-gpt4"
)

View results in LangSmith to compare:

• Latency
• Token usage
• Cost
• Quality (with custom evaluators)

Viewing Logs

Via CLI

## Stream logs in real-time
langgraph deployment logs my-agent-prod --follow

## View recent logs
langgraph deployment logs my-agent-prod --limit 100

## Filter by level
langgraph deployment logs my-agent-prod --level ERROR

Via LangSmith UI

Logs are included in each trace - expand trace to see full logs.

Best Practices

Use Consistent Tagging

# Good: Consistent tags
tags=["production", "premium-tier", "chat-feature"]

# Bad: Inconsistent tags
tags=["prod", "Premium User", "CHAT"]

Add Business Context

metadata={
    "user_id": "[e-mail]",
    "user_tier": "premium",
    "cost_center": "sales",
    "session_id": "sess_123",
    "request_source": "mobile_app"
}

Monitor Key Metrics Daily

Check daily:

• Error rate (should be < 1%)
• P95 latency (should be < 5s)
• Daily cost (should be within budget)
• User satisfaction (via feedback)

Set Up Alerts

Configure alerts for:

• Error rate > 5%
• P95 latency > 5s
• Daily cost > $100
• Budget 80% consumed

Troubleshooting

No traces appearing

Solution:

• Verify LANGSMITH_TRACING=true in environment
• Check LangSmith API key is set
• Confirm correct project name
• Make test request to generate trace

Traces missing metadata

Solution:

# Ensure metadata is passed to invoke
config = RunnableConfig(
    tags=["your-tags"],
    metadata={"user_id": "alice"}
)
result = await graph.ainvoke(input, config=config)

High latency in traces

Investigation:

1. Expand trace to see timing breakdown
2. Identify slowest step
3. Optimize:
   • LLM calls: Try faster model or smaller prompts
   • Tool calls: Add caching or parallel execution
   • State operations: Optimize state size

Next Steps

LangSmith Tracing

Complete LangSmith guide

CI/CD

Automate deployments

Configuration

Optimize configuration

Quickstart

Deploy your agent

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All set! Your LangGraph Platform deployment is automatically monitored with comprehensive LangSmith tracing.