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What Are Coding Agents?

Coding agents are specialized programs that can communicate with LLM APIs in an intelligent loop and execute tool calls. When you mention @blocks, one of these agents processes your request, understands your codebase, and provides assistance. Each agent has different capabilities, model architectures, and optimal use cases.

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Available Agents

Blocks currently supports three coding agents:

Claude Code

The go-to for many developers

Codex

High-reasoning capabilities for complex tasks and critical reviews

Gemini CLI

Best for simple tasks

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Agent Comparison

Here’s a quick comparison to help you choose:
FeatureClaude CodeCodexGemini CLI
ProviderAnthropicOpenAIGoogle
Latest ModelsClaude 4.5 Sonnet, Claude 4.5 OpusGPT 5.2Gemini 3 Pro
Best ForHigh-performance and consistencyHigh complexity workSimple tasks
StatusStableStableExperimental
Can Set as Default Agent?YesYesNo
Gemini CLI is currently experimental and may have different behavior or limitations compared to the other agents.

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Setting Up Agents

To use any agent, you need to configure authentication:
1

Choose Authentication Method

Each agent supports different authentication options:Claude Code:
  • Anthropic API key (Get one)
  • Anthropic subscription (Claude Pro/Team)
  • AWS Bedrock API key (for enterprise)
Codex:
  • OpenAI API key (Get one)
  • OpenAI subscription (ChatGPT Plus/Team)
Gemini CLI:
2

Configure in Dashboard

  1. Go to Blocks Dashboard
  2. Navigate to Dashboard → Agents
  3. Select your agent and authentication method
  4. Enter credentials or connect subscription
3

Set Default Agent

When multiple agents are configured, choose which agent to use by default:
  1. In Dashboard → Agents
  2. Select “Set as default agent” from the preferred agent’s dropdown menu
Learn more: Setting Your Default Agent

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Using Different Agents

Once configured, you have two ways to use specific agents:

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1. Default Agent

Your default agent is used automatically for all requests unless you specify otherwise: 
@blocks can you review this code?
This uses whatever agent you set as default in your preferences.

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2. Slash Commands

Override the default agent for specific requests using slash commands: 
@blocks /claude review this complex architecture
@blocks /codex quickly implement this API endpoint
@blocks /gemini analyze this large codebase
Use slash commands to leverage the strengths of different agents for different tasks, even if you have a default set.

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Agent-Specific Details

Each agent has unique capabilities and configuration options. Learn more about each:

Claude Code

Detailed guide to Claude Code capabilities, models, and best practices

Codex

Complete Codex documentation including model selection and tips

Gemini CLI

Experimental Gemini CLI features and setup instructions

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Security

Your API keys and subscription tokens are:
  • Encrypted at rest and in transit
  • Never shared with other users
  • Only used to authenticate the agent on your behalf
  • Workspace-specific (each workspace has its own keys)
You can update your agent credentials at any time from the Dashboard.
Never share your API keys publicly. Each user should use their own API keys, especially in organization workspaces.

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Cost Considerations

When you use Blocks:
  • API calls are made using your API keys or Subscriptions
  • You are billed directly by the AI provider (Anthropic, OpenAI, or Google)
  • Blocks does not charge for API usage
  • Monitor your usage in each provider’s console
Different agents have different pricing:

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Switching Between Agents

You can change your default agent at any time:
  1. Go to Blocks Dashboard → Agents
  2. Change the Default Agent selection
The change takes effect immediately for all new sessions. Existing sessions will still have the previous credentials
Consider setting different default agents for different workspaces based on the type of work done in each.

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Next Steps

Claude Code Guide

Learn about Claude Code’s capabilities and best practices

Codex Guide

Explore Codex’s features and optimal use cases

Gemini CLI Guide

Discover experimental Gemini CLI features

Set Default Agent

Configure your preferred default agent