fix(agent-development): add SDK examples, update model references

[cpfiffer]

Summary

Fixes the agent-development skill to include proper SDK examples and updated model references.

Issue: Users reported the skill suggested incorrect CLI syntax for creating agents.

Changes

• Add minimal working example at top of Quick Start section
• Add Python/TypeScript SDK examples for agent creation
• Clarify that letta-code CLI uses --new-agent flag interactively
• Update model references to current models (GPT-4o, Claude Sonnet 4, Gemini 2.0)
• Remove outdated GPT-5/Claude 4.5 references
• Fix custom tool example with proper source_code pattern
• Remove stale date references

Files Modified

• letta/agent-development/SKILL.md
• letta/agent-development/references/architectures.md
• letta/agent-development/references/model-recommendations.md
• letta/agent-development/references/tool-patterns.md

Reported by: wunluv (Discord, Jan 19, 2026)

Written by Cameron ◯ Letta Code

[cpfiffer]

@letta-code please review

[github-actions]

Letta Code finished @cpfiffer's task —— View job

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Reviewing PR #32

• Review SKILL.md changes
• Review architectures.md changes
• Review model-recommendations.md changes
• Review tool-patterns.md changes
• Post comprehensive review

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Review: agent-development skill update

✅ Approved

This PR makes excellent improvements to the agent-development skill. The changes address the reported Discord issue (wunluv, Jan 19) and significantly improve the skill's usability.

What's Good

SDK Examples:

• Added minimal working example at top of Quick Start - excellent for quick discovery
• Both Python and TypeScript examples use correct SDK patterns
• Proper model handle format (openai/gpt-4o, anthropic/claude-sonnet-4-20250514)
• TypeScript correctly uses memoryBlocks (camelCase) vs Python's memory_blocks

Model Updates:

• Removed references to unreleased/future models (GPT-5, Claude 4.5)
• Updated to current production models (GPT-4o, Claude Sonnet 4, Gemini 2.0)
• Added model handle strings for easy copy-paste

Custom Tool Example (tool-patterns.md):

• Now shows complete working pattern with source_code parameter
• Includes proper docstring with Args/Returns
• Shows how to attach tool to agent

Quality Improvements:

• Removed stale date references ("October 2025", "November 2025")
• More professional language ("Russian roulette" → "Inconsistent tool calling")
• CLI note correctly references --new-agent flag (updated in v0.12.9+)

No Issues Found

All technical content verified accurate against current SDK patterns.

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