QA Agent

A Q&A assistant with tool calling capabilities.

Difficulty: Intermediate

What You'll Learn

• LangGraph bind_tools() for tool calling
• ReAct pattern (reason then act)
• Tool policy enforcement
• Multiple HTTP endpoints

Available Tools

Tool	Description	HTTP Access
get_current_time	Current UTC time	None (local)
calculate	Math expressions	None (local)
lookup_fact	Wikipedia lookup	Wikipedia API

Setup

agentvisor template create langgraph/qa-agent
cd qa-agent
docker compose up -d
agentvisor serve .

Test It

THREAD=$(curl -sX POST http://localhost:8090/threads | jq -r '.thread_id')

# Time query (uses tool)
curl -sX POST "http://localhost:8090/threads/$THREAD/runs?wait=60s" \
    -H "Content-Type: application/json" \
    -d '{"input": {"messages": [{"role": "user", "content": "What time is it?"}]}}'

# Calculator (uses tool)
curl -sX POST "http://localhost:8090/threads/$THREAD/runs?wait=60s" \
    -H "Content-Type: application/json" \
    -d '{"input": {"messages": [{"role": "user", "content": "Calculate sqrt(144) + 10"}]}}'

# Wikipedia (HTTP call through proxy)
curl -sX POST "http://localhost:8090/threads/$THREAD/runs?wait=60s" \
    -H "Content-Type: application/json" \
    -d '{"input": {"messages": [{"role": "user", "content": "Tell me about Python programming"}]}}'

Key Code

Tool Binding

from langchain_core.tools import tool

@tool
def calculate(expression: str) -> str:
    """Evaluate a mathematical expression."""
    # ... implementation

llm = ChatOllama(...)
llm_with_tools = llm.bind_tools([get_current_time, calculate, lookup_fact])

ReAct Graph

builder.add_node("assistant", assistant)
builder.add_node("tools", ToolNode(ALL_TOOLS))

builder.add_conditional_edges(
    "assistant",
    should_continue,
    {"tools": "tools", "end": END}
)
builder.add_edge("tools", "assistant")

Policy Highlights

# Tool allowlist
annotations:
  - name: "allowed_tools"
    value:
      - "get_current_time"
      - "calculate"
      - "lookup_fact"

# HTTP allowlist (Ollama + Wikipedia)
annotations:
  - name: "allowed_patterns"
    value:
      - "^ollama.*"
      - "^en\\.wikipedia\\.org(/.*)?$"

Next Steps

• Task Agent: Human-in-the-loop workflows