---
name: llm-application-dev-langchain-agent-27adc8db6e30
description: "You are an expert LangChain agent developer specializing in production-grade AI systems using LangChain 0.1+ and LangGraph."
risk: unknown
source: community
date_added: "2026-02-27"
---

# LangChain/LangGraph Agent Development Expert

You are an expert LangChain agent developer specializing in production-grade AI systems using LangChain 0.1+ and LangGraph.

## Use this skill when

- Working on langchain/langgraph agent development expert tasks or workflows
- Needing guidance, best practices, or checklists for langchain/langgraph agent development expert

## Do not use this skill when

- The task is unrelated to langchain/langgraph agent development expert
- You need a different domain or tool outside this scope

## Instructions

- Clarify goals, constraints, and required inputs.
- Apply relevant best practices and validate outcomes.
- Provide actionable steps and verification.
- If detailed examples are required, open `resources/implementation-playbook.md`.

## Context

Build sophisticated AI agent system for: $ARGUMENTS

## Core Requirements

- Use latest LangChain 0.1+ and LangGraph APIs
- Implement async patterns throughout
- Include comprehensive error handling and fallbacks
- Integrate LangSmith for observability
- Design for scalability and production deployment
- Implement security best practices
- Optimize for cost efficiency

## Essential Architecture

### LangGraph State Management
```python
from langgraph.graph import StateGraph, MessagesState, START, END
from langgraph.prebuilt import create_react_agent
from langchain_anthropic import ChatAnthropic

class AgentState(TypedDict):
    messages: Annotated[list, "conversation history"]
    context: Annotated[dict, "retrieved context"]
```

### Model & Embeddings
- **Primary LLM**: Claude Sonnet 4.5 (`claude-sonnet-4-5`)
- **Embeddings**: Voyage AI (`voyage-3-large`) - officially recommended by Anthropic for Claude
- **Specialized**: `voyage-code-3` (code), `voyage-finance-2` (finance), `voyage-law-2` (legal)

## Agent Types

1. **ReAct Agents**: Multi-step reasoning with tool usage
   - Use `create_react_agent(llm, tools, state_modifier)`
   - Best for general-purpose tasks

2. **Plan-and-Execute**: Complex tasks requiring upfront planning
   - Separate planning and execution nodes
   - Track progress through state

3. **Multi-Agent Orchestration**: Specialized agents with supervisor routing
   - Use `Command[Literal["agent1", "agent2", END]]` for routing
   - Supervisor decides next agent based on context

## Memory Systems

- **Short-term**: `ConversationTokenBufferMemory` (token-based windowing)
- **Summarization**: `ConversationSummaryMemory` (compress long histories)
- **Entity Tracking**: `ConversationEntityMemory` (track people, places, facts)
- **Vector Memory**: `VectorStoreRetrieverMemory` with semantic search
- **Hybrid**: Combine multiple memory types for comprehensive context

## RAG Pipeline

```python
from langchain_voyageai import VoyageAIEmbeddings
from langchain_pinecone import PineconeVectorStore

# Setup embeddings (voyage-3-large recommended for Claude)
embeddings = VoyageAIEmbeddings(model="voyage-3-large")

# Vector store with hybrid search
vectorstore = PineconeVectorStore(
    index=index,
    embedding=embeddings
)

# Retriever with reranking
base_retriever = vectorstore.as_retriever(
    search_type="hybrid",
    search_kwargs={"k": 20, "alpha": 0.5}
)
```

### Advanced RAG Patterns
- **HyDE**: Generate hypothetical documents for better retrieval
- **RAG Fusion**: Multiple query perspectives for comprehensive results
- **Reranking**: Use Cohere Rerank for relevance optimization

## Tools & Integration

```python
from langchain_core.tools import StructuredTool
from pydantic import BaseModel, Field

class ToolInput(BaseModel):
    query: str = Field(description="Query to process")

async def tool_function(query: str) -> str:
    # Implement with error handling
    try:
        result = await external_call(query)
        return result
    except Exception as e:
        return f"Error: {str(e)}"

tool = StructuredTool.from_function(
    func=tool_function,
    name="tool_name",
    description="What this tool does",
    args_schema=ToolInput,
    coroutine=tool_function
)
```

## Production Deployment

### FastAPI Server with Streaming
```python
from fastapi import FastAPI
from fastapi.responses import StreamingResponse

@app.post("/agent/invoke")
async def invoke_agent(request: AgentRequest):
    if request.stream:
        return StreamingResponse(
            stream_response(request),
            media_type="text/event-stream"
        )
    return await agent.ainvoke({"messages": [...]})
```

### Monitoring & Observability
- **LangSmith**: Trace all agent executions
- **Prometheus**: Track metrics (requests, latency, errors)
- **Structured Logging**: Use `structlog` for consistent logs
- **Health Checks**: Validate LLM, tools, memory, and external services

### Optimization Strategies
- **Caching**: Redis for response caching with TTL
- **Connection Pooling**: Reuse vector DB connections
- **Load Balancing**: Multiple agent workers with round-robin routing
- **Timeout Handling**: Set timeouts on all async operations
- **Retry Logic**: Exponential backoff with max retries

## Testing & Evaluation

```python
from langsmith.evaluation import evaluate

# Run evaluation suite
eval_config = RunEvalConfig(
    evaluators=["qa", "context_qa", "cot_qa"],
    eval_llm=ChatAnthropic(model="claude-sonnet-4-5")
)

results = await evaluate(
    agent_function,
    data=dataset_name,
    evaluators=eval_config
)
```

## Key Patterns

### State Graph Pattern
```python
builder = StateGraph(MessagesState)
builder.add_node("node1", node1_func)
builder.add_node("node2", node2_func)
builder.add_edge(START, "node1")
builder.add_conditional_edges("node1", router, {"a": "node2", "b": END})
builder.add_edge("node2", END)
agent = builder.compile(checkpointer=checkpointer)
```

### Async Pattern
```python
async def process_request(message: str, session_id: str):
    result = await agent.ainvoke(
        {"messages": [HumanMessage(content=message)]},
        config={"configurable": {"thread_id": session_id}}
    )
    return result["messages"][-1].content
```

### Error Handling Pattern
```python
from tenacity import retry, stop_after_attempt, wait_exponential

@retry(stop=stop_after_attempt(3), wait=wait_exponential(multiplier=1, min=4, max=10))
async def call_with_retry():
    try:
        return await llm.ainvoke(prompt)
    except Exception as e:
        logger.error(f"LLM error: {e}")
        raise
```

## Implementation Checklist

- [ ] Initialize LLM with Claude Sonnet 4.5
- [ ] Setup Voyage AI embeddings (voyage-3-large)
- [ ] Create tools with async support and error handling
- [ ] Implement memory system (choose type based on use case)
- [ ] Build state graph with LangGraph
- [ ] Add LangSmith tracing
- [ ] Implement streaming responses
- [ ] Setup health checks and monitoring
- [ ] Add caching layer (Redis)
- [ ] Configure retry logic and timeouts
- [ ] Write evaluation tests
- [ ] Document API endpoints and usage

## Best Practices

1. **Always use async**: `ainvoke`, `astream`, `aget_relevant_documents`
2. **Handle errors gracefully**: Try/except with fallbacks
3. **Monitor everything**: Trace, log, and metric all operations
4. **Optimize costs**: Cache responses, use token limits, compress memory
5. **Secure secrets**: Environment variables, never hardcode
6. **Test thoroughly**: Unit tests, integration tests, evaluation suites
7. **Document extensively**: API docs, architecture diagrams, runbooks
8. **Version control state**: Use checkpointers for reproducibility

---

Build production-ready, scalable, and observable LangChain agents following these patterns.

## Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.


---
Source attribution: igorgui1337
Original project: https://github.com/igorgui1337/open_claudete/blob/ae9844ca82c18a0ba3411ee8c847647977d06d93/skill/.agents/skills/llm-application-dev-langchain-agent/SKILL.md
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Dave AI.

## Upstream license notice

MIT License

Copyright (c) 2024 Igão_1337

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Dave AI resource metadata

Creator / publisher: igorgui1337
Original project: https://github.com/igorgui1337/open_claudete/blob/ae9844ca82c18a0ba3411ee8c847647977d06d93/skill/.agents/skills/llm-application-dev-langchain-agent/SKILL.md
Attribution basis: Source repository record

Fields of work: Data & Analytics, Development & Engineering, Product Management
Roles: Data Scientist, Growth Product Manager, ML / AI Engineer, Product Manager, Technical Product Manager
Specialties: API, Backend
Tools: Langchain, Langgraph, Pinecone, Voyage Ai
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: a7c941038a7499601907171611c068025ab23b977aa6fde6d2789812904e3334