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Agents are assigned to specific Claude models based on task complexity and computational requirements.
Model Distribution Summary
Model
Agent Count
Use Case
Fable
0
Longest-horizon autonomous work (tier above Opus; see criteria)
Opus
55
Critical architecture, security, code review, production coding
Sonnet
71
Complex tasks, support with intelligence
Haiku
25
Fast operational tasks
Inherit
52
Complex tasks where the user chooses the model at runtime
Model Selection Criteria
Haiku - Fast Execution & Deterministic Tasks
Use when:
Generating code from well-defined specifications
Creating tests following established patterns
Writing documentation with clear templates
Executing infrastructure operations
Performing database query optimization
Handling customer support responses
Processing SEO optimization tasks
Managing deployment pipelines
Sonnet - Complex Reasoning & Architecture
Use when:
Designing system architecture
Making technology selection decisions
Performing security audits
Reviewing code for architectural patterns
Creating complex AI/ML pipelines
Providing language-specific expertise
Orchestrating multi-agent workflows
Handling business-critical legal/HR matters
Fable - Longest-Horizon Autonomous Work
Claude Fable 5 (model: fable) is the tier above Opus. It is opt-in in Claude Code
(v2.1.170+, never the default) and carries roughly 2.6× the effective cost of Opus
($10/$50 per MTok plus a ~30% heavier tokenizer), so reserve it for agents where Opus
demonstrably needs multiple attempts.
Security-analysis agents — Fable 5's cyber/bio safety classifiers fall back to
Opus 4.8 on that content anyway
Anything Sonnet or Opus already completes in one pass
Other harnesses map fable to their top available model (see
authoring.md). Fable-tier agent bodies should state goals
and constraints rather than step-by-step scaffolding, and must not ask the model to echo
its internal reasoning.
Hybrid Orchestration Patterns
The plugin ecosystem leverages Sonnet + Haiku orchestration for optimal performance and cost efficiency:
Pattern 1: Planning → Execution
Sonnet: backend-architect (design API architecture)
↓
Haiku: Generate API endpoints following spec
↓
Haiku: test-automator (generate comprehensive tests)
↓
Sonnet: code-reviewer (architectural review)
Agents can be invoked through natural language when you need Claude to reason about which specialist to use:
"Use backend-architect to design the authentication API"
"Have security-auditor scan for OWASP vulnerabilities"
"Get performance-engineer to optimize this database query"
Slash Commands
Many agents are accessible through plugin slash commands for direct invocation:
/backend-development:feature-development user authentication
/security-scanning:security-sast
/incident-response:smart-fix "memory leak in payment service"