agentlens-monitor 0.4.1

LLM observability, quality scoring, hallucination detection, cost tracking, agent run debugging, and drop-in LangChain + LlamaIndex callbacks — in 2 lines of code.

llm-evaltrack

Drop-in observability for LLM applications. Automatic quality scoring, hallucination detection, cost tracking, and agent run debugging — with 2 lines of code.

Install

pip install agentlens-monitor

Quick Start

import agentlens

agentlens.init(api_url="https://www.agentlens.one/ingest")
agentlens.patch_openai()     # auto-track all OpenAI calls
agentlens.patch_anthropic()  # auto-track all Anthropic calls

That's it. Your existing code is unchanged. Every chat.completions.create() and messages.create() is now automatically tracked.

LlamaIndex (v0.4.0)

Drop-in callback handler for RAG pipelines built with LlamaIndex — every query, retrieval, LLM call, and agent step shows up as a span.

import llm_observe
from llm_observe.integrations.llama_index import AgentLensLlamaIndexHandler
from llama_index.core import Settings
from llama_index.core.callbacks import CallbackManager

llm_observe.init(api_url="https://www.agentlens.one/ingest")
Settings.callback_manager = CallbackManager([AgentLensLlamaIndexHandler()])

# Any LlamaIndex query is now traced automatically

Requires llama-index-core installed.

LangChain (v0.3.0)

Drop-in callback handler — attach it once and every chain, LLM call, tool, and retriever shows up as a span in the AgentLens trace view.

import llm_observe
from llm_observe.integrations.langchain import AgentLensCallbackHandler

llm_observe.init(api_url="https://www.agentlens.one/ingest")
handler = AgentLensCallbackHandler(trace_name="my_qa_chain")

# Works with any LangChain runnable, chain, or agent
chain.invoke({"input": "..."}, config={"callbacks": [handler]})

What gets captured per run:

• Top-level chain → one AgentLens trace
• Nested chains, LLM calls, tool calls, retriever calls → spans (with parent/child)
• Models, prompts, outputs, token counts, errors — all wired through automatically

Requires langchain-core (or the full langchain package) installed.

Agent Debugging (v0.2.0)

Trace multi-step agent runs to see every step, find where things break, and measure cost per span:

from agentlens import trace_agent

with trace_agent("research_agent", input="Research renewable energy trends") as trace:

    with trace.span("web_search", span_type="retrieval") as s:
        results = search("renewable energy 2024")
        s.set_output(results)

    with trace.span("llm_summarize", span_type="llm", model="gpt-4o") as s:
        summary = llm.summarize(results)
        s.set_output(summary)
        s.set_tokens(1200)
        s.set_cost(0.009)

    with trace.span("fact_check", span_type="tool") as s:
        verified = fact_check(summary)
        s.set_output(verified)

    trace.set_output("Report complete")

Span types: llm · tool · retrieval · decision · custom

Each trace captures: total duration, tokens, cost, per-step timing, inputs/outputs, and errors. Errors inside a with block are automatically caught and marked as failed.

What Gets Tracked (auto)

Field	Source
Input / Output	Message content
Model	response.model
Tokens	response.usage
Cost (USD)	Calculated from token counts
Quality Score	Heuristic evaluation or LLM judge
Hallucination flags	Automatic detection

Manual Tracking

agentlens.track_llm_call(
    input="What is the capital of France?",
    output="Paris.",
    prompt="You are a helpful assistant.",
    model="gpt-4o",
    metadata={"feature": "qa", "user_id": "u_123", "cost_usd": 0.0003},
)

Configuration

agentlens.init(
    api_url="https://www.agentlens.one/ingest",
    api_key="your-secret",   # optional bearer token
    max_retries=3,
    timeout=5.0,
    enabled=True,            # set False in tests
)

Dashboard

Pair with the self-hosted server for:

• Real-time quality trend charts
• Bad response categorization
• Root-cause analysis by prompt
• Cost vs quality per model
• Regression alerts
• Agent Debugger — waterfall timeline of every span in a trace

Live demo: www.agentlens.one

Self-host: github.com/Soufianeazz/llm-evaltrack

Changelog

v0.4.0

• Added AgentLensLlamaIndexHandler for LlamaIndex — one callback captures queries, retrievals, LLM calls, agent steps, and function calls as spans
• Parent/child span tree built automatically from LlamaIndex event tree

v0.3.0

• Added AgentLensCallbackHandler for LangChain — one callback captures every chain, LLM call, tool call, and retriever call as a waterfall span tree
• Supports nested chains via LangChain run_id / parent_run_id
• Graceful import fallback if langchain-core isn't installed

v0.2.0

• Added trace_agent() context manager for agent run tracing
• Added span() and trace.span() for individual steps
• Spans support: set_output(), set_tokens(), set_cost(), set_error()
• Automatic error capture on exceptions inside with blocks
• Nested span support via parent_span_id

v0.1.0

• Initial release: patch_openai(), patch_anthropic(), track_llm_call()