# Introduction

[![PyPI](https://img.shields.io/pypi/v/fiddler-langchain)](https://pypi.org/project/fiddler-langchain/)

## Overview

Complete API reference documentation for the `fiddler-langchain` package, which instruments [LangChain V1](https://docs.langchain.com/oss/python/langchain/overview) agents (the `langchain.agents.create_agent` API and middleware pattern) and exports OpenTelemetry traces to Fiddler.

```bash
pip install fiddler-langchain
```

```python
from fiddler_langchain import FiddlerLangChainInstrumentor
```

## Components

### Attributes

Span and session attribute helpers. `add_span_attributes` attaches component-scoped attributes to a specific model, retriever, or tool. `add_session_attributes` and `set_conversation_id` are re-exported from `fiddler-otel` and propagate through every span in the current trace context.

* [add\_session\_attributes](/api/fiddler-langchain-sdk/attributes/add-session-attributes.md)
* [add\_span\_attributes](/api/fiddler-langchain-sdk/attributes/add-span-attributes.md)
* [set\_conversation\_id](/api/fiddler-langchain-sdk/attributes/set-conversation-id.md)

### Tracing

Instrumentation entry points and LLM context helpers. `FiddlerLangChainInstrumentor` is the one-time setup that wires the Fiddler exporter into LangChain; `FiddlerAgentMiddleware` is a drop-in agent middleware that emits spans for LLM, tool, and chain steps; `set_llm_context` and `clear_llm_context` attach and remove retrieval context (e.g. retrieved documents) on the active model so it appears on its LLM spans.

* [clear\_llm\_context](/api/fiddler-langchain-sdk/tracing/clear-llm-context.md)
* [FiddlerAgentMiddleware](/api/fiddler-langchain-sdk/tracing/fiddler-agent-middleware.md)
* [FiddlerLangChainInstrumentor](/api/fiddler-langchain-sdk/tracing/fiddler-lang-chain-instrumentor.md)
* [set\_llm\_context](/api/fiddler-langchain-sdk/tracing/set-llm-context.md)


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