🧠 Best LLM APIs for AI Agents

Which LLM inference APIs can agents call reliably, without phone verification or captchas? We rated every major model provider on discovery, account creation friction, agent tooling quality, reliability, and pricing model. Ranked by Agent Native Score.

OpenAI
llms.txt
85

GPT-4, o1, DALL-E, Whisper, and Embeddings APIs. The most widely adopted AI API with extensive ecosystem support.

Discovery
90
Account creation
80
Agent tooling
90
Reliability
70
Pricing model
75
Structured outputs, function calling, and JSON mode work well. No official MCP server. Reliability has improved but still occasional outages. No free tier (must add payment method).
Mistral AI
Free tierSandbox
85

European LLM provider with strong function calling and agent capabilities. Mistral Large and Codestral are top-tier models for code-heavy agents.

Discovery
88
Account creation
85
Agent tooling
88
Reliability
82
Pricing model
83
OpenAI-compatible API makes drop-in replacement easy. Excellent tool/function calling. La Plateforme gives instant API keys. Codestral model particularly good for coding agents. No MCP server but OpenAPI spec available.
Groq
Free tier
84

LPU-based LLM inference at 500+ tokens/second. OpenAI-compatible API. Runs Llama, Gemma, Mixtral, Whisper, and other open models.

Discovery
82
Account creation
88
Agent tooling
85
Reliability
78
Pricing model
90
Fastest LLM inference available (500+ tokens/second on LPU). OpenAI-compatible drop-in replacement. Free developer tier with rate limits. Excellent for latency-sensitive agents. No free tier for production.
Google AI (Gemini)
MCPFree tierSandbox
84

Google's Gemini API for developers. Gemini 1.5 Pro has 1M context window and native function calling. Available via Google AI Studio or Vertex AI.

Discovery
88
Account creation
82
Agent tooling
88
Reliability
87
Pricing model
78
Google AI Studio provides instant API keys. Generous free tier. Gemini 1.5 Pro/Flash excellent for multimodal agents. Function calling, code execution, and grounding with Google Search all available. Vertex AI version requires GCP account setup.
Anthropic (Claude API)
llms.txt
83

Claude API. State-of-the-art language models with native tool use, computer use, and MCP support built in.

Discovery
90
Account creation
85
Agent tooling
95
Reliability
70
Pricing model
55
Created the MCP protocol. Native tool use is class-leading. Prompt caching reduces costs for agents with long contexts. No free tier. API access occasionally waitlisted.
Perplexity API
83

Search-augmented LLM inference API. Models return answers with citations from live web search — ideal for agents that need current information.

Discovery
85
Account creation
85
Agent tooling
86
Reliability
80
Pricing model
80
OpenAI-compatible API. Sonar models include live web search grounding. Great for agents that need to answer questions about current events or recent docs. No free tier — pay-as-you-go from first query. Structured citations available.
Cohere
Free tier
82

Enterprise NLP platform. Command-R models optimized for retrieval-augmented generation and tool use. Strong structured output support.

Discovery
85
Account creation
83
Agent tooling
86
Reliability
82
Pricing model
75
Command-R+ is designed specifically for tool use and RAG. Trial key available instantly. Connectors feature enables agents to add live data sources. No MCP server. Enterprise pricing tiers may be limiting for small agent projects.
Cerebras
Free tier
81

Ultra-fast LLM inference. Runs Llama-3 and other open models at 2000+ tokens/sec — an order of magnitude faster than GPU clouds.

Discovery
82
Account creation
85
Agent tooling
82
Reliability
78
Pricing model
80
OpenAI-compatible API makes integration trivial. Primarily valuable for latency-sensitive agents. Llama-3.3-70B runs at 1800+ tokens/sec. Function calling supported. Newer service — smaller ecosystem than OpenAI/Groq but remarkable raw speed.
Cloudflare
Free tier
80

CDN, DDoS protection, DNS, Workers (serverless), KV, R2 storage, AI Gateway, and more. Extensive free tier.

Discovery
85
Account creation
80
Agent tooling
75
Reliability
95
Pricing model
65
Exceptional reliability (99.99%+ uptime). Workers free tier is very useful for agents. API surface is large — agents need scoped tokens to avoid confusion. No official MCP server yet.
Together AI
Free tier
80

Inference API for open-source models (Llama, Mistral, Qwen, etc.). OpenAI-compatible API, fast inference, and fine-tuning support.

Discovery
75
Account creation
88
Agent tooling
80
Reliability
78
Pricing model
82
OpenAI-compatible API for open-source models. Drop-in replacement for agents using OpenAI SDK. Free $1 credit on signup. Competitive pricing vs. proprietary models. Good for cost-conscious agent deployments.
Hugging Face
llms.txtFree tier
78

ML model hub with 500k+ models. Serverless inference API, Spaces for demos, Datasets hub, and Inference Endpoints for dedicated hosting.

Discovery
92
Account creation
85
Agent tooling
72
Reliability
70
Pricing model
70
Largest ML model hub. Serverless Inference API for 150k+ models. Free tier is rate-limited but functional. Has llms.txt. No official MCP server. Inference Endpoints for dedicated hosting (paid).
Replicate
76

Run ML models via REST API — image generation, audio, video, text, and custom models. Pay per prediction, no GPU management.

Discovery
80
Account creation
80
Agent tooling
72
Reliability
70
Pricing model
78
Run any ML model via REST without managing GPUs. Clean API: POST model + inputs, poll for output. GitHub-based signup. Pay-per-prediction. Community models include Flux, Stable Diffusion, Llama. No free tier.

Give your agents access to the full registry

Add Agent Native Registry as an MCP server. Your agents can search, compare, and select tools at runtime.

claude mcp add --transport http agentnative https://agentnativeregistry.com/api/mcp