---
title: Claude API for AI Agents
description: "Build AI agents on the Claude API with apiToken.sale: one key for every model, streaming, tool use, prompt caching and a lifetime key spending limit for long-run cost control."
url: https://apitoken.sale/docs/learn/claude-api-for-ai-agents
language: en
---

# Using the Claude API for AI agents

Agentic workloads are token-hungry and long-running, which makes model choice, caching and cost control matter most. Here is how apiToken.sale fits agents.

## What agents need

- Streaming and tool use — both standard on the Anthropic Messages API.
- Model routing: Haiku for cheap steps, Sonnet for reasoning, Opus for the hardest.
- Prompt caching for repeated system prompts and tool definitions.
- A per-key lifetime spending limit so a runaway loop cannot spend beyond that key's cap.

## A cost-aware agent loop

A practical pattern: route planning and reasoning to Sonnet, cheap sub-steps and parsing to Haiku, and escalate only the hardest calls to Opus. Cache the system prompt and tool definitions so repeated context is nearly free.

- Set a per-key lifetime spending limit so a runaway loop cannot spend beyond the cap.
- Stream so the agent can act on partial output.
- Watch token usage to tune which steps use which model.

## Frequently asked questions

### Is the Claude API good for agents?

Yes — with streaming, tool use, model routing and prompt caching, all on one apiToken.sale key with spend controls.

### How do I keep agent costs down?

Route cheap steps to Haiku, cache repeated context, and set a lifetime spending limit on the agent's key.

---
Get a key: https://apitoken.sale/register
More guides: https://apitoken.sale/docs/learn