Claude Opus 5.5
Claude Opus 5.5 is Anthropic's new flagship, succeeding Claude Opus 5. It is built for demanding reasoning, coding and long-horizon agentic work, and it is at its best when a task spans many files and many steps rather than a single prompt. A 1M-token context window keeps the whole codebase in view, and it runs on Hoodgen AI now.
Technical Specifications
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What is Claude Opus 5.5?
Claude Opus 5.5 is Anthropic's frontier model for work that has to be right rather than fast. It succeeds Claude Opus 5 and focuses on multi-step changes across large codebases: refactors that touch dozens of files, migrations, and agentic loops that have to stay coherent for hours. It accepts text, images and files, returns text, and pairs a 1M-token context window with up to 128,000 tokens of output per response, so a long diff lands in one pass instead of a dozen fragments.
Features & Capabilities
Frontier Reasoning
Opus-class depth on the hardest reasoning and planning tasks.
Multi-File Editing
Strongest at changes that ripple across a large codebase, not one file.
1M Context
A million tokens of working memory for repositories, specs and logs.
Long-Horizon Agents
Stays coherent across long autonomous runs instead of drifting.
Text, Image and File Input
Screenshots, design mockups and documents alongside code.
128K Output
Long diffs, test suites and reports in a single response.
Who Is Claude Opus 5.5 For?
Large Codebase Refactors
Renames, migrations and architectural changes that span many modules.
Agentic Engineering Loops
Agents that plan, edit, run tests and iterate until the task closes.
Hard Reasoning Tasks
Analysis and design work where a wrong first answer is expensive.
Document and Spec Review
Long PDFs and design docs read alongside the code they describe.
Claude Opus 5.5 Pricing
- $4.00 per million input tokens, $20.00 per million output tokens
- Prompt caching cuts repeat-context cost substantially for agentic loops
- Run it from your Hoodgen free credits, no credit card required
- Higher allowances on Hoodgen AI paid plans
What Makes Claude Opus 5.5 Different?
Opus 5.5 is the top of Anthropic's line, so the interesting question is not whether it is smart but where the extra intelligence pays for itself. It shows up on tasks with a long tail of small decisions: a refactor where the compiler keeps finding one more caller, or an agent that has to remember a constraint it was told ninety steps ago. On short, well-scoped prompts the gap against cheaper models is small; on multi-file work it is not.
The 1M-token window and the 128,000-token output ceiling are what make those long tasks practical. Instead of chunking a repository into pieces and losing coherence between them, you hand over the whole thing and get a complete change set back. That single-pass behaviour is the real upgrade over Opus 5 for engineering work.
At $4 input and $20 output per million tokens it is a premium model, and the sensible pattern is to reserve it for the steps that decide the outcome. Draft, triage and summarise on a cheaper sibling, then hand the difficult edit or the final review to Opus 5.5. Hoodgen keeps both on the same account, so switching mid-task costs nothing.
Claude Opus 5.5 Performance & Pricing
Anthropic now sells three tiers of the 5.5 generation, all with a 1M-token context window. Pick by how much of the task is hard rather than by raw capability.
What Can You Do With Claude Opus 5.5?
Reach for Opus 5.5 when the cost of a wrong answer is higher than the cost of the tokens. It is the model to point at a subsystem you do not fully understand, a migration with no obvious end, or an investigation that spans code, logs and documentation at once.
Best Use Cases
- Refactoring a subsystem you inherited
- Planning and executing a multi-step migration
- Reviewing a large diff for correctness
- Debugging that needs hypothesis testing across files
- Design work where tradeoffs must be argued, not guessed
Claude Opus 5.5 Privacy & Data Policy
Claude Opus 5.5 is developed by Anthropic and served through OpenRouter. Prompts and completions are processed by Anthropic's API under Anthropic's terms.
As with any third-party model, avoid pasting passwords, personal data or source code you would not share with an external provider. Hoodgen AI keeps cheaper and free models on the same account, so you can move a task elsewhere without losing your work.
Claude Opus 5.5 vs Other Models
Frequently Asked Questions
Hand the hard task to the flagship
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