LangChain tools, retrievers, retrieval, and structured output

Overview

• A retriever returns candidate documents for a query.
• A tool exposes an action with a description and argument schema.
• Structured-output wrappers ask supported models for typed data and help parse the result; these are adapters around the concepts already learned.

Why this matters

Consistent component contracts make swapping retrieval engines or model integrations easier.

An everyday example

Standard connectors let one device work with several compatible accessories.

A technical example

Wrap your authorized policy search in a retriever, and wrap getClaimStatus as a schema-defined tool.

How it works

1. Implement business operation
2. Add schema/adapter
3. Call component or expose to agent
4. Validate result
5. Trace underlying service call.

Architecture and flow

Agent/chain → LangChain adapter → authorized business/search service → typed result.

The insurance assistant example

A retriever always derives tenant filters from verified request context, even if the model asks for another tenant.

When to use it

Shared components and replaceable provider/vector integrations.

When to avoid it

Do not place authorization only in prompt instructions or rely on a wrapper to infer tenant isolation.

Interview answer

“The framework standardizes interfaces; my services remain responsible for permissions, source quality, validation, and domain errors.”

Benefits, trade-offs, and production considerations

• Inspect whether structured output uses provider schema support or tool-based strategies.
• Cap tool outputs and retrieve document IDs before loading large content.
• Protect direct calls to the adapter as well as calls made through an agent.