langchain-middleware

Add human-in-the-loop approval and custom middleware to LangChain agent tool calls.

1|1|Updated Mar 13, 2026
One-click install
npx skills add https://github.com/woody1234567/Rag_system_interview --skill langchain-middleware-woody1234567
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: langchain-middleware
Source: https://github.com/woody1234567/Rag_system_interview/tree/main/.agents/skills/langchain-middleware
Command: npx skills add https://github.com/woody1234567/Rag_system_interview --skill langchain-middleware-woody1234567

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires langchain, and includes scripts (resource) and references (resource) components.

What problem does it solve?

LangChain agents can be enhanced with human-in-the-loop (HITL) approval for sensitive operations, custom middleware for additional processing, and structured output for better integration.

Core Features & Use Cases

  • Human-in-the-Loop Middleware: Pause and approve sensitive tool calls to avoid errors.
  • Custom Middleware: Intercept tool calls for enhanced error handling, logging, and retry logic.
  • Structured Output: Ensure consistent and usable outputs with Pydantic/Zod.

Quick Start

Activate the skill and provide human approval for the 'send_email' tool with the 'approve' decision.

Frequently Asked Questions about langchain-middleware

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I add human-in-the-loop approval to LangChain agent tool calls?

Human-in-the-loop approval for LangChain agent tool calls is implemented by intercepting tool executions with middleware hooks, pausing the agent process, and resuming based on your explicit approve or reject decision.

What is custom middleware used for in LangChain agents?

Custom middleware in LangChain agents is used to intercept tool calls, enabling you to inject additional processing logic such as enhanced error handling, operational logging, and automated retry mechanisms.

How do I get structured output from a LangChain agent for system integration?

Structured output from a LangChain agent is achieved by enforcing consistent and usable data schemas using Pydantic or Zod, ensuring the generated responses can seamlessly integrate with other external systems.

Does this middleware require a specific LangChain agent setup to function?

Yes, this middleware requires an existing LangChain agent environment equipped with configured tools that specifically support middleware hooks to successfully intercept and process tool outputs.

What is the best way to pause sensitive tool calls in LangChain for manual review?

Pausing sensitive tool calls in LangChain for manual review is best handled through human-in-the-loop middleware, which intercepts the operation and waits for a direct human approval before execution proceeds.