langsight 0.3.3

Agent runtime reliability — prevent loops, enforce budgets, monitor MCP health, scan for CVEs

LangSight

Your agent failed. Which tool broke — and how do we stop it next time?

Detect loops. Enforce budgets. Break failing tools. Map blast radius. For MCP servers: health checks, security scanning, schema drift detection.

Not another prompt, eval, or simulation platform. LangSight is the runtime reliability layer for AI agent toolchains.

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Where LangSight fits

Langfuse watches the brain (model outputs, token costs, evals). LangWatch tests the brain (simulations, prompt optimization). Datadog watches the body (CPU, memory, HTTP codes). LangSight watches the hands (tools the agent calls, their health, safety, and cost).

Question	Best tool
Did the prompt/model perform well?	LangWatch / Langfuse / LangSmith
Should I change prompts or eval policy?	LangWatch / Langfuse / LangSmith
Is my server CPU/memory healthy?	Datadog / New Relic
Which tool call failed in production?	LangSight
Is my agent stuck in a loop?	LangSight
Is an MCP server unhealthy or drifting?	LangSight
Is an MCP server exposed or risky?	LangSight
Why did this session cost $47 instead of $3?	LangSight
If this tool goes down, which agents break?	LangSight

Use LangSight alongside Langfuse and LangWatch — not instead of them.

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The problem

LLM quality is only half the problem. Teams already have ways to inspect prompts and eval scores. What they still cannot answer fast enough:

• Agent stuck in a loop — retries the same tool 47 times, burns $200, produces nothing
• MCP server degraded silently — schema changed, latency spiked, auth expired. Agent keeps calling, gets bad data
• Cost explosion — sub-agent retries geocoding-mcp endlessly. Nobody knows until the invoice arrives
• Cascading failure — postgres-mcp goes down. 3 agents depend on it. All sessions fail. No blast radius visibility
• Unsafe MCP server — 66% of community MCP servers have critical code smells. No automated scanning

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What LangSight does

1. Prevent — stop failures before users notice

from langsight.sdk import LangSightClient

client = LangSightClient(
    url="http://localhost:8000",
    loop_detection=True,        # detect same tool+args called 3x → auto-stop
    max_cost_usd=1.00,          # hard budget limit per session
    max_steps=25,               # hard step limit
    circuit_breaker=True,       # auto-disable tools after 5 consecutive failures
)

• Loop detection — same tool called with same args 3x → session terminated, alert fired
• Budget guardrails — max cost / max steps per session → hard stop before bill shock
• Circuit breaker — tool fails 5x → auto-disabled for cooldown → alert → auto-recovery test

2. Detect — see what broke and why

$ langsight sessions --id sess-f2a9b1

Trace: sess-f2a9b1  (support-agent)  [LOOP_DETECTED]
5 tool calls · 1 failed · 2,134ms · $0.023

sess-f2a9b1
├── jira-mcp/get_issue        89ms  ✓
├── postgres-mcp/query        42ms  ✓
├──  → billing-agent          handoff
│   ├── crm-mcp/update    120ms  ✓
│   └── slack-mcp/notify    —   ✗  timeout
Root cause: slack-mcp timed out at 14:32 UTC

• Action traces — every tool call in every session, with latency, status, cost
• Multi-agent trees — full call tree across agent handoffs via parent_span_id
• Run health tags — every session auto-classified: success, loop_detected, budget_exceeded, tool_failure

3. Monitor — MCP health + security

$ langsight mcp-health

Server              Status    Latency     Schema    Circuit
snowflake-mcp       ✅ UP     142ms       Stable    closed
slack-mcp           ⚠️ DEG   1,240ms     Stable    closed
jira-mcp            ❌ DOWN   —           —         open (5 failures)
postgres-mcp        ✅ UP     31ms        Changed   closed

$ langsight security-scan

CRITICAL  jira-mcp        CVE-2025-6514  Remote code execution in mcp-remote
HIGH      slack-mcp       OWASP-MCP-01   Tool description contains injection pattern
HIGH      postgres-mcp    OWASP-MCP-04   No authentication configured

• MCP health checks — continuous ping, latency, uptime tracking
• Schema drift detection — tool schemas change → alert fires before agents hallucinate
• Security scanning — CVE (OSV), OWASP MCP Top 10, tool poisoning detection, auth audit

4. Attribute — cost at the tool level

$ langsight costs --hours 24

Tool                    Calls   Failed   Cost       % of Total
geocoding-mcp           2,340   12       $1,872     44.6%
postgres-mcp/query      890     3        $445       10.6%
claude-3.5 (LLM)       156     0        $312       7.4%

Not model-level costs (Langfuse does that). Tool-level costs. Which MCP server is burning your budget?

5. Map — blast radius via lineage

postgres-mcp ❌ DOWN

Impact:
  - support-agent: 200 sessions/day (HIGH)
  - billing-agent: 50 sessions/day (MEDIUM)
  - data-agent: 10 sessions/day (LOW)

Total: ~260 sessions/day affected
Circuit breaker: active (auto-disabled 3 minutes ago)

• Lineage DAG — which agents call which tools
• Blast radius — if this tool goes down, what else breaks?
• Impact alerts — "postgres-mcp is DOWN — 3 agents affected, 260 sessions/day"

6. Investigate — AI-assisted root cause

$ langsight investigate jira-mcp

Investigation: jira-mcp
├── Health: DOWN since 14:32 UTC (3 consecutive failures)
├── Schema: 2 tools changed (get_issue dropped 'priority' field)
├── Recent errors: 429 Too Many Requests (rate limit)
└── Recommendation: check API rate limits, restore 'priority' field

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Quick start

Prerequisites

• Docker and Docker Compose
• Python 3.11+ and uv

1. Clone and start

git clone https://github.com/LangSight/langsight.git
cd langsight
./scripts/quickstart.sh

Takes ~2 minutes. Generates secrets, starts 5 containers, seeds demo data.

2. Open the dashboard

http://localhost:3003 — log in with [e-mail] / admin.

3. Instrument your agent

from langsight.sdk import LangSightClient

client = LangSightClient(url="http://localhost:8000", api_key="<from quickstart>")
traced = client.wrap(mcp_session, server_name="postgres-mcp", agent_name="my-agent")
result = await traced.call_tool("query", {"sql": "SELECT * FROM orders"})

Two lines. Every tool call is now traced, guarded, and cost-attributed.

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Alerting

Channel	Status
Slack (Block Kit)	Shipped
Generic webhook	Shipped
OpsGenie (native Events API)	v0.3
PagerDuty (Events API v2)	v0.3

Alert types: server down/recovered, schema drift, latency spike, SLO breach, anomaly, loop detected, budget exceeded, circuit breaker open, failure rate spike, blast radius impact.

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Architecture

  Agent Frameworks                    ┌──────────────────────────────────┐
  (LangGraph, CrewAI,                 │         LangSight Platform        │
   Pydantic AI, etc.)                │                                  │
         │                            │  ┌──────────┐ ┌──────────────┐  │
         │ SDK (trace + guard)        │  │ Health   │ │  Security    │  │
         ▼                            │  │ Checker  │ │  Scanner     │  │
  ┌─────────────┐                     │  └────┬─────┘ └──────┬───────┘  │
  │    OTEL     │────────────────────►│       │              │          │
  │  Collector  │                     │       ▼              ▼          │
  └─────────────┘                     │  ┌───────────────────────────┐  │
                                      │  │       ClickHouse          │  │
  MCP Servers                         │  │  traces · health · costs  │  │
  ┌──────────┐                        │  └───────────────────────────┘  │
  │ server-1 │◄──────────────────────►│  ┌───────────────────────────┐  │
  │ server-2 │   health + security    │  │       PostgreSQL          │  │
  │ server-N │                        │  │  users · alerts · SLOs    │  │
  └──────────┘                        │  └───────────────────────────┘  │
                                      │                                 │
                                      │  ┌──────────┐ ┌─────────────┐  │
                                      │  │ FastAPI  │ │ Dashboard   │  │
                                      │  │ REST API │ │ Next.js 15  │  │
                                      │  └──────────┘ └─────────────┘  │
                                      └──────────────────────────────────┘

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Integrations

Framework	Integration
LangGraph	LangSightLangGraphCallback
LangChain / Langflow	LangSightLangChainCallback
CrewAI	LangSightCrewAICallback
OpenAI Agents SDK	LangSightOpenAIHooks
Anthropic / Claude Agent SDK	AnthropicToolTracer
Pydantic AI	@langsight_tool decorator
Claude Desktop / Cursor / VS Code	Auto-discovered by langsight init
Any OTEL framework	OTLP endpoint

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CLI reference

Command	Description
langsight init	Auto-discover MCP servers, generate config
langsight sessions	List sessions with health tags, costs, failures
langsight sessions --id <id>	Full trace for one session
langsight mcp-health	Health status + circuit breaker state
langsight security-scan	CVE + OWASP MCP + poisoning detection
langsight monitor	Continuous monitoring with alerts
langsight costs	Cost attribution by tool, agent, session
langsight investigate	AI-assisted failure investigation

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Development

uv sync --dev && docker compose up -d
uv run pytest -m unit                    # no Docker needed
uv run pytest -m integration             # requires Docker
uv run pytest --cov=langsight            # with coverage
uv run mypy src/ && uv run ruff check src/

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Security

LangSight monitors MCP security — it must itself be secure. Report vulnerabilities via GitHub Security Advisories.

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License

Apache 2.0 — free to use, modify, distribute, and build on. See LICENSE.