Claude Opus 4.5
Claude Opus 4.5 is an Anthropic Opus model built for high-reasoning coding, tool use, and long-running agentic work. Until November 24, 2025, Opus pricing pushed most daily coding workflows toward Sonnet. Claude Opus 4.5 changed that by cutting the tier from $15/$75 to $5/$25 per million tokens.
That 67% price reduction is the product shift that matters most. Opus moved from an escalation choice for rare hard tasks to a model teams can use more often for planning, difficult debugging, review, and complex code changes.
For agentic workflows, the practical question is not only whether Opus 4.5 is strong, but where it should be routed. Teams can reserve it for high-judgment planning and verification while using lower-cost models for routine implementation steps.
Verdent fits that pattern through Parallel Power, where a stronger planning model can coordinate lower-cost worker agents without spending Opus tokens on every action. This guide explains what changed in Claude Opus 4.5, how it performs on coding work, and how to compare it with Claude Opus 4.7 and GPT-5 for real development workflows.
Claude Opus 4.5 Overview
Anthropic released Claude Opus 4.5 on November 24, 2025.
The Claude API model ID is claude-opus-4-5-20251101.
The model is built for:
- Agentic coding
- Long-running software tasks
- Tool use
- Deep research
- Computer use
- Multi-agent coordination
Claude Opus 4.5 fits work where reasoning quality matters more than raw speed. Good use cases include cross-file refactors, ambiguous production bugs, migration planning, security-sensitive review, complex test repair, and tasks that require a model to inspect files, use tools, revise a plan, and produce a controlled diff.
It is less necessary for routine edits. Documentation updates, simple component changes, small test additions, and mechanical cleanup can often run on a faster or cheaper worker model, as long as the work still passes tests and review.
New projects should also test newer Claude models. Later Opus models may be a better default for new evaluations.
What's New vs Claude Opus 4
Claude Opus 4.5 improved the Opus 4 workflow in several areas.
It offered stronger coding scores, better terminal work, lower API pricing, and effort control.
The biggest practical change was cost. Opus 4.5 reduced Opus 4’s original API pricing from $15 input and $75 output to $5 input and $25 output per million tokens.
That made high-end Opus workflows more practical for long coding tasks. A team could use Opus 4.5 earlier in the workflow instead of saving it only for escalations. For example, Opus 4.5 could inspect a bug report, read the relevant files, create a plan, and decide which implementation steps can be delegated to cheaper workers.
Effort control also matters for agentic coding. Some tasks need deeper reasoning and longer tool use; others need a short edit and a fast answer. A practical setup is to increase effort for architecture, root-cause analysis, and final review, then reduce effort for narrow file edits once the plan is clear.
Coding & SWE-bench Scores
Anthropic reported strong coding results for Claude Opus 4.5.
| Benchmark | Claude Opus 4.5 |
|---|---|
| SWE-bench Verified | 80.9% |
| Terminal-Bench 2.0 | 59.3% |
| MCP Atlas | 62.3% |
| OSWorld | 66.3% |
These are vendor-reported results. They depend on the test setup.
For real software work, evaluate the full workflow. A model score does not guarantee safe changes in your repository.
The practical test is whether Claude Opus 4.5 can make a correct change after reading your conventions, build scripts, failing tests, dependency constraints, and deployment rules. Use representative tickets, require diffs instead of broad explanations, and compare pass rate, review effort, token spend, and rework against your current model mix.
A strong workflow should include:
- A clear issue statement and acceptance criteria
- Repository context and relevant files
- A planned diff before broad edits
- Tests or static checks that match the change
- Human or model review before merge
- Rollback awareness for risky changes
Verdent Reviewer helps inspect generated changes before integration.
Comparing Claude Opus 4.5 against GPT-5.1 Codex on the same tickets can make differences in diff quality, test recovery, and review effort easier to see.
For source-level validation, Anthropic documentation is worth checking after you understand the Claude Opus 4.5 workflow described here.
Claude Opus 4.5 vs Opus 4.8
Claude Opus 4.8 is newer than Claude Opus 4.5. It is generally the better default if both are available.
| Area | Opus 4.5 | Opus 4.8 |
|---|---|---|
| Release | November 2025 | April 2026 |
| Strength | Strong coding at lower cost | Better hard-task reliability |
| Price | $5 input / $25 output | Similar listed rate |
| Verdent status | Not built-in in current list | Built-in in current list |
Use Opus 4.5 for stable legacy workflows. Use Opus 4.8 or newer for new evaluations.
A team may keep Claude Opus 4.5 when an existing workflow is already validated, prompts are tuned to its behavior, and regression risk matters more than adopting the newest model. A team should test Opus 4.8 or newer when starting a new agentic workflow, handling harder tasks, or trying to reduce failed runs and review cycles.
Strong Models Still Need a Quality System
A higher benchmark score does not eliminate Quality Roulette. Complex edits still need isolated work, tests, and a second review pass.
Verdent reported 76.1% on SWE-bench Verified. Its Production-Ready Quality combines strong models with Code Verification instead of treating the model as the entire product.
Review Claude output with another model.
Comparing Opus 4.5 with Gemma 3 can clarify when a smaller open model is sufficient versus when Claude’s stronger agentic reliability is worth the cost.
When details such as limits or setup steps matter, Reddit can help confirm the latest implementation surface.
Using Claude Opus 4.5 in Verdent
Claude Opus 4.5 is not in Verdent’s current published built-in model list.
Two routes may work:
- Use Claude Code through BYOA.
- Check Anthropic BYOK availability.
For BYOA, configure Claude Code in Verdent. Then set the desired Claude model if supported by your account.
For BYOK, add an Anthropic key and check the available model list.
This is conditional access. It is not the same as native built-in Verdent support.
A sensible Verdent setup is to reserve Opus 4.5 for planning, diagnosis, and final review while assigning implementation steps to faster workers. In that pattern, Opus 4.5 reads the task, identifies the risky files, creates the plan, and reviews the final diff. Worker models handle routine edits, test additions, and narrow implementation tasks.
This keeps the expensive model focused on decisions that shape the change. Verdent’s review and verification flow then helps catch regressions before the work is merged.
If Opus 4.5 is reserved for planning and review, Grok 4 can be compared as another option for reasoning-heavy Verdent workflows.
Before you budget a real project around Claude Opus 4.5, compare the claims here with Mckaywrigley.
Pricing
Claude Opus 4.5 API pricing is:
- $5 per million input tokens
- $25 per million output tokens
- $0.50 per million cache hits
- Higher cache-write rates depending on duration
The lower Opus 4.5 rate changes how teams can budget high-reasoning work. A long coding run can still become expensive when it reads many files, writes large patches, or repeats the same context across attempts. The best cost control is not only choosing a cheaper model; it is routing each step to the right model.
Use Opus 4.5 where a bad decision is costly: architecture, root-cause analysis, migration strategy, security review, and final acceptance review. Use faster workers for repetitive implementation after the plan is clear. Use cache-friendly prompts and stable repository context when possible, because repeated context can drive token spend.
Verdent pricing may differ for built-in models. BYOK and BYOA use provider billing.
Frequently Asked Questions
Is Claude Opus 4.5 still available?
Anthropic still marks Claude Opus 4.5 as active. Availability can still depend on account, API access, region, and the integration path you use.
Is it the newest Opus model?
No. Newer Opus models are available. Use Claude Opus 4.5 for validated legacy workflows, and test newer Opus models when starting new work.
Is it built into Verdent?
No. Claude Opus 4.5 is not in Verdent’s current published built-in model list. Use BYOA or BYOK if your account and provider access support it.
Is Opus 4.5 good for coding?
Yes. Anthropic reported 80.9% on SWE-bench Verified for Claude Opus 4.5. Treat that as a useful signal, not a guarantee that every repository change will be safe or correct.
Should I use Opus 4.5 or Opus 4.8?
Use Opus 4.8 or newer for new work when it is available. Use Opus 4.5 for validated legacy workflows, tuned prompts, or teams that need stable behavior from an existing setup.
Spend Opus Tokens Where They Change the Decision
Use Opus for architecture, difficult debugging, migration planning, and review. Route routine implementation to faster workers, then verify the final diff before merge.
Put Claude Opus 4.5 on Harder Work
Use Claude Opus 4.5 for architecture, difficult debugging, and high-stakes review while routing routine implementation to faster models in Verdent.