Claude Opus 4 5 Migration
One-shot repo sweep to retarget Sonnet 4.0/4.5 or Opus 4.1 model IDs, strip unsupported betas, and add Opus 4.5 effort settings across Anthropic, Bedrock, Vertex, and Azure.
Overview
Claude Opus 4.5 Migration is an agent skill most often used in Build (also Operate, Ship) that migrates model strings and prompts from Sonnet 4.0, Sonnet 4.5, or Opus 4.1 to Opus 4.5 across major Claude hosting platforms
Install
npx skills add https://github.com/anthropics/claude-code --skill claude-opus-4-5-migrationWhat is this skill?
- 6-step migration workflow: search → update model strings → remove context-1m beta → set effort to high → summarize → off
- Platform table for Opus 4.5 IDs on Anthropic API, AWS Bedrock, Google Vertex AI, and Azure AI Foundry
- Explicit exclusion: does not migrate Haiku 4.5
- Documents unsupported context-1m-2025-08-07 beta with inline comment pattern
- References effort.md for high-effort parameter configuration on Opus 4.5
- 4 hosting platforms in the model string table
- Effort parameter set to high per references/effort.md
Adoption & trust: 7.2k installs on skills.sh; 131k GitHub stars; 3/3 security scanners passed (skills.sh audits).
What problem does it solve?
Your repo still points at Sonnet or older Opus IDs, unsupported betas, and pre-4.5 prompt habits, so upgrades silently break or underperform on Opus 4.5.
Who is it for?
Solo builders upgrading an existing Claude-powered app or agent workflow when Anthropic ships Opus 4.5 and you need Bedrock, Vertex, or Azure strings correct the first time.
Skip if: Greenfield projects already authored for Opus 4.5, Haiku 4.5-only stacks, or teams that only need conceptual model comparisons without touching code.
When should I use this skill?
User wants to update codebase, prompts, or API calls from Sonnet 4.0, Sonnet 4.5, or Opus 4.1 to Opus 4.5; not for Haiku 4.5.
What do I get? / Deliverables
You get consistent Opus 4.5 model strings per platform, removed unsupported beta headers, high effort configured, and a change summary plus an open door for prompt tweaks if quality shifts.
- Updated model strings and API call sites
- Migration summary of all changes
- Comments noting removed unsupported beta headers
Recommended Skills
Journey fit
Spans multiple journey phases - primary shelf plus alternate fits below.
Model string and prompt retuning lives in the codebase and agent config—the canonical Build shelf for anything that wires Claude into your product. Agent-tooling is where API clients, SDK calls, and prompt packs are edited when you swap foundation models.
Where it fits
Retarget SDK defaults and env-based model IDs before shipping a new agent feature.
Freeze release branch with correct Opus 4.5 strings across staging and production configs.
Roll forward after a cloud catalog update without leaving stale Sonnet identifiers in lambdas or workers.
How it compares
Structured migration checklist for Opus 4.5—not a generic “pick any model” tuning chat.
Common Questions / FAQ
Who is claude-opus-4-5-migration for?
Indie developers and agent builders maintaining codebases that call Claude via Anthropic, Bedrock, Vertex, or Azure and need a repeatable upgrade from Sonnet 4.x or Opus 4.1.
When should I use claude-opus-4-5-migration?
During Build when wiring new agent-tooling, before Ship launch when freezing API configs, and in Operate iterate when rolling out a provider’s Opus 4.5 endpoint—any time the user asks to migrate prompts or model strings to Opus 4.5.
Is claude-opus-4-5-migration safe to install?
It instructs broad repo search and edits to API calls; review the Security Audits panel on this Prism page and diff changes before merging to production.
SKILL.md
READMESKILL.md - Claude Opus 4 5 Migration
# Opus 4.5 Migration Guide One-shot migration from Sonnet 4.0, Sonnet 4.5, or Opus 4.1 to Opus 4.5. ## Migration Workflow 1. Search codebase for model strings and API calls 2. Update model strings to Opus 4.5 (see platform-specific strings below) 3. Remove unsupported beta headers 4. Add effort parameter set to `"high"` (see `references/effort.md`) 5. Summarize all changes made 6. Tell the user: "If you encounter any issues with Opus 4.5, let me know and I can help adjust your prompts." ## Model String Updates Identify which platform the codebase uses, then replace model strings accordingly. ### Unsupported Beta Headers Remove the `context-1m-2025-08-07` beta header if present—it is not yet supported with Opus 4.5. Leave a comment noting this: ```python # Note: 1M context beta (context-1m-2025-08-07) not yet supported with Opus 4.5 ``` ### Target Model Strings (Opus 4.5) | Platform | Opus 4.5 Model String | |----------|----------------------| | Anthropic API (1P) | `claude-opus-4-5-20251101` | | AWS Bedrock | `anthropic.claude-opus-4-5-20251101-v1:0` | | Google Vertex AI | `claude-opus-4-5@20251101` | | Azure AI Foundry | `claude-opus-4-5-20251101` | ### Source Model Strings to Replace | Source Model | Anthropic API (1P) | AWS Bedrock | Google Vertex AI | |--------------|-------------------|-------------|------------------| | Sonnet 4.0 | `claude-sonnet-4-20250514` | `anthropic.claude-sonnet-4-20250514-v1:0` | `claude-sonnet-4@20250514` | | Sonnet 4.5 | `claude-sonnet-4-5-20250929` | `anthropic.claude-sonnet-4-5-20250929-v1:0` | `claude-sonnet-4-5@20250929` | | Opus 4.1 | `claude-opus-4-1-20250422` | `anthropic.claude-opus-4-1-20250422-v1:0` | `claude-opus-4-1@20250422` | **Do NOT migrate**: Any Haiku models (e.g., `claude-haiku-4-5-20251001`). ## Prompt Adjustments Opus 4.5 has known behavioral differences from previous models. **Only apply these fixes if the user explicitly requests them or reports a specific issue.** By default, just update model strings. **Integration guidelines**: When adding snippets, don't just append them to prompts. Integrate them thoughtfully: - Use XML tags (e.g., `<code_guidelines>`, `<tool_usage>`) to organize additions - Match the style and structure of the existing prompt - Place snippets in logical locations (e.g., coding guidelines near other coding instructions) - If the prompt already uses XML tags, add new content within appropriate existing tags or create consistent new ones ### 1. Tool Overtriggering Opus 4.5 is more responsive to system prompts. Aggressive language that prevented undertriggering on previous models may now cause overtriggering. **Apply if**: User reports tools being called too frequently or unnecessarily. **Find and soften**: - `CRITICAL:` → remove or soften - `You MUST...` → `You should...` - `ALWAYS do X` → `Do X` - `NEVER skip...` → `Don't skip...` - `REQUIRED` → remove or soften Only apply to tool-triggering instructions. Leave other uses of emphasis alone. ### 2. Over-Engineering Prevention Opus 4.5 tends to create extra files, add unnecessary abstractions, or build unrequested flexibility. **Apply if**: User reports unwanted files, excessive abstraction, or unrequested features. Add the snippet from `references/prompt-snippets.md`. ### 3. Code Exploration Opus 4.5 can be overly conservative about exploring code, proposing solutions without reading files. **Apply if**: User reports the model proposing fixes without inspecting relevant code. Add the snippet from `references/prompt-snippets.md`. ### 4. Frontend Design **Apply if**: User requests improved frontend design quality or reports generi