Claude Opus 5.5 API

Access Anthropic Claude Opus 5.5—also searched as Opus 5.5— through EvoLink's unified chat API. Test long-context coding, tool use, prompt caching before integrating.

AnthropicText GenerationAvailable

From $3.800 / 1M input tokens$4.000 official price-5%

API docs

Always-on thinkingEffort controlTool usePrompt cachingWeb search toolChat + Messages API

Production routeLive

Live

Context

1M context · 128K max output

Best For

Long-running agentic coding, analyst-grade knowledge work, chart and screenshot reading

Input

Text + images

Output

Text · JSON (structured output) · tool calls

Models Pricing Readme API

Choose Claude Opus 5.5

Anthropic’s newest Opus model for long-running agentic coding, knowledge work, and visual analysis, at a lower list price than Claude Opus 5. Five billing dimensions — input, cache write, cache read, output, and the web search tool — are metered separately.

Claude Opus 5.5

Anthropic’s newest Opus model

Selected

Model ID

claude-opus-5-5

Best for

Multi-step coding in a real repository, pull-request review, analyst-grade reports and financial models, and reading dense charts, diagrams, and screenshots — work where a better answer at a lower per-token price removes effort downstream.

Input

$3.800 / 1M-5%

258.4 cr / 1M$4.000official price

Cache write

$4.750 / 1M-5%

323 cr / 1M$5.000official price

Cache read

$0.192 / 1M-4%

13 cr / 1M$0.200official price

Output

$19.000 / 1M-5%

1292 cr / 1M$20.000official price

All rates are per 1M tokens, shown in USD and credits, and reflect your account's current pricing.

Claude Opus 5.5 pricing

Estimate what one Claude Opus 5.5 request costs before you integrate. The calculator uses your account's current rates, with official pricing as a reference.

Request calculator

Enter the token mix for one request and the number of successful tool calls.

Input tokensCache write tokensCache read tokensOutput tokensWeb search

Estimated request cost

Claude Opus 5.5

USD$0.0096

Credits0.6486

Official estimate $0.011 · save $0.0006 (5%)

Input tokens0.2584 cr

Cache write tokens0 cr

Cache read tokens0.0026 cr

Output tokens0.3876 cr

Minimum charge: 0.01 credits per request.

Budget guide

Approximate requests using the current token mix.

Add credits

$10

About 1048 requests

For quick testing

$50

About 5242 requests

For regular development

$100

About 10484 requests

For production evaluation

Server-side tool rates

Only successful server-side calls are billed per call; failed attempts have no tool fee, but tokens still apply.

Web search$0.010/ call0.68 cr / call

Claude Opus 5.5 API for long-running coding and knowledge work

Call Anthropic’s newest Opus model through EvoLink’s unified API at $3.800 / $19.000 per million input / output tokens. Opus 5.5 succeeds Claude Opus 5 at a lower list price, keeps the 1,000,000-token context window and 128K max output, and runs with thinking always on — effort is the control for depth, latency, and cost.

Claude Opus 5.5 is served on EvoLink under the model ID claude-opus-5-5 through Chat Completions · Anthropic Messages, with the same API key and balance you use for every other model. It offers a 1M context window and up to 128K output tokens, plus long-context coding, tool use, prompt caching.

Claude Opus 5.5 specs and capabilities

Numbers come from the EvoLink route configuration; capabilities are what the API exposes today.

Context window: 1M tokens
Max output: 128K tokens
Input: Text + images
Output: Text · JSON (structured output) · tool calls
Reasoning: Always-on reasoning
Tool use: Function calling with multi-step tool sequences
Prompt caching: Cache write + cache read rates
Server-side tools: Web search, billed per successful call
Protocols: Chat Completions · Anthropic Messages
Model ID: claude-opus-5-5

Where Claude Opus 5.5 is the right Opus route

Opus 5.5 costs less per token than Opus 5 and, in Anthropic’s testing, often finishes the same task with fewer tokens. Route to it by the value of a completed task, then tune effort before touching the prompt.

Multi-step coding in a real repository

Carry a change through a large codebase until the tests pass, review pull requests, and plan multi-file refactors. Anthropic reports that at the default medium effort it matched or beat Claude Opus 5 at high effort on such tasks, in fewer steps. Measure accepted patches, not snippet quality.

Analyst-grade knowledge work

Long analytical deliverables, financial models, and audits of large document sets. Anthropic reports it is much less likely than Opus 5 to state a figure or cite a source the inputs do not support, so check citations against your own evidence set.

Charts, diagrams, and screenshots

Read dense charts, diagrams, and UI screenshots where meaning depends on position — which boxes an arrow connects, or what changed between two versions. Anthropic reports higher visual accuracy than Opus 5 at every effort level, often without cropping tools.

When another route is the better choice

Everyday coding, high-volume agents, classification, and latency-sensitive chat usually belong on Claude Sonnet 5. Claude Fable 5.1 is the escalation for the hardest reasoning. Keep Claude Opus 5 only where a workload is already validated on it and you have not re-tested yet.

Two ways to use Claude Opus 5.5: EvoLink API or Agent

Use the EvoLink API for product backends and batch jobs, or call Claude Opus 5.5 from Codex, Claude, or Gemini for coding and analysis workflows. Both paths share the same EvoLink API key, balance, model ID, and request history.

Option 1

Integrate with the EvoLink API

Best for: product backends, batch jobs, automated pipelines

Send OpenAI-compatible Chat Completions (or Anthropic Messages) requests to EvoLink and control the model ID, system prompt, output budget, tools, and structured output.

1Create an EvoLink API key in the console
2Point your OpenAI or Anthropic SDK at the EvoLink base URL and select the model ID shown above
3Send one representative request and read the usage field for input, cached, and output tokens
4Set max_tokens and retries per task; keep tool-call IDs and results across turns

Create EvoLink API Key

Option 2

Call it with an Agent

Best for: coding, review, and analysis tasks in Codex, Claude, and Gemini

Give the Agent the task, the inputs to include, and the acceptance criteria. It assembles the request, calls Claude Opus 5.5 through EvoLink, and returns the answer with token usage.

1Set EVOLINK_API_KEY in your local environment; never put it in code or a prompt
2Describe the task, the inputs to include, and the expected output format
3Ask the Agent to call Claude Opus 5.5 through EvoLink and show the request before sending
4Let the Agent report the answer, token usage, and any error body

Claude Opus 5.5 API code example and error handling

This example shows the shortest runnable request: an OpenAI-compatible Chat Completions call with a system prompt, a user message, and an output budget. Open the API tab for the complete parameter and response reference.

View complete API docs

cURL

curl -X POST https://api.evolink.ai/v1/chat/completions \
  -H "Authorization: Bearer $EVOLINK_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-5-5",
    "messages": [
      { "role": "system", "content": "You are a senior engineer reviewing a pull request." },
      { "role": "user", "content": "Review this diff and list the blocking issues with file and line:\n<diff>" }
    ],
    "max_tokens": 16000
  }'

# Anthropic Messages is also available at /v1/messages with the same model
# ID.
# Thinking is always on for this model and counts toward max_tokens, so
# leave room for it. The response includes choices[0].message and a usage
# object (prompt_tokens, completion_tokens, and cache read / write tokens
# when caching applies).

Invalid request or unsupported parameter

Check the model ID, the messages array, and parameter ranges against the API reference; remove fields this route does not support.

Authentication or balance issue

Check the Authorization bearer token and confirm the available balance in the console.

Context length exceeded

Prompt tokens exceed the Claude Opus 5.5 context window. Trim or retrieve only the relevant evidence and reuse cached prefixes.

Rate limited (429)

Back off and retry with jitter; batch or queue requests instead of sending parallel bursts.

Content or tool call rejected

Review sensitive content, malformed tool-call arguments, and JSON schema mismatches before retrying.

Move from Claude Opus 5 to Opus 5.5 without replacing your stack

Keep one EvoLink client and API key. Most requests carry over unchanged; the four steps below cover the settings that behave differently on Opus 5.5.

Switch the model ID

Point the client at EvoLink, keep the same API key, and select claude-opus-5-5. Both the OpenAI-compatible Chat Completions endpoint and the Anthropic Messages endpoint accept it.

Low migration

Remove thinking-off settings

Thinking cannot be switched off on Opus 5.5 at any effort level. Drop thinking: disabled and budget_tokens, omit the thinking field or send adaptive, and read response content by block type rather than position.

Breaking change

Set effort explicitly

The default effort is medium, one level below Claude Opus 5’s high. Start at medium, test low and high on your own tasks, and lower effort before adding “think less” instructions to the prompt.

Tune

Route tasks by completed-task value

Compare success rate, retries, output tokens, cache hits, wall-clock time, and human correction against Claude Opus 5 and Sonnet 5 on replayed production samples — not token price alone.

Evaluate

Prompt caching for repeated agent context

Cache stable system prompts and tool schemas to reuse context across agent turns. Writes and reads are billed separately. Anthropic lists cache reads at 5% of its input rate; use EvoLink’s displayed write and read prices to budget for cache hits and misses.

1M-token context with a 128K max output

Keep connected code, specifications, documents, and agent state in one working context. Thinking counts toward max_tokens, so leave room for it: for long agentic coding turns, 64K is a reasonable starting point.

Thinking is always on — effort is the only control

Opus 5.5 always uses adaptive thinking, with medium effort by default. Anthropic rejects thinking: disabled and budget_tokens. EvoLink converts these legacy settings to adaptive thinking for compatibility; they cannot turn thinking off. Prefer omitting thinking or sending adaptive, and tune effort explicitly.

Forced tool choice is not supported

Forced tool choice is unsupported: Messages any/tool and Chat Completions required/named functions return an error. With auto, clearly request the tool and verify that a call occurred; auto does not guarantee one. Notes between tool calls may arrive as thinking blocks, so parse content by block type.

Claude Opus 5.5: five billing dimensions, metered separately

Claude Opus 5.5 does not bill as a single blended rate. Knowing which dimension a workload consumes — and that thinking is billed as output — is what keeps an Opus budget predictable.

Input and output tokens

$3.800 per 1M input tokens and $19.000 per 1M output tokens on EvoLink, compared with Anthropic’s $4.000 and $20.000. Thinking always runs and is billed as output even when its text is not returned, so size max_tokens for the thinking plus the reply.

5-minute cache writes and cache reads

Storing a prefix for 5 minutes costs $4.750 per 1M tokens; reusing it costs $0.192 per 1M tokens. Anthropic’s official cache-read rate is 5% of its input rate. EvoLink rates are rounded, so use the displayed prices when estimating savings.

Web search tool

Billed per search at $0.010. Search results also enter the request as ordinary input tokens, so a research-heavy turn pays both the per-search fee and the tokens it pulls in.

Compare Claude routes after workload testing

EvoLink

First check whether Opus 5.5 reduces retries and review effort on your own tasks at the effort level you plan to run. Then compare price, context, caching, and workload fit to choose the production route.

Model	Claude Opus 5.5	Claude Opus 5	Claude Sonnet 5
Input / output	$3.8 / $19	$4.75 / $23.75	$1.8 / $9
Context	1M	1M	1M
Caching	Read + write	Read + write	Read + write
Best for	Multi-step coding in a real repository, pull-request review, analyst-grade reports and financial models, and reading dense charts, diagrams, and screenshots — work where a better answer at a lower per-token price removes effort downstream.	The previous Opus flagship at a higher list price; keep it where a workload is already validated and not yet re-tested.	Opus-class coding and agent performance at a balanced Sonnet rate for everyday production traffic.

Claude Opus 5.5

Input / output$3.8 / $19

Context1M

CachingRead + write

Best forMulti-step coding in a real repository, pull-request review, analyst-grade reports and financial models, and reading dense charts, diagrams, and screenshots — work where a better answer at a lower per-token price removes effort downstream.

Claude Opus 5

Input / output$4.75 / $23.75

Context1M

CachingRead + write

Best forThe previous Opus flagship at a higher list price; keep it where a workload is already validated and not yet re-tested.

Claude Sonnet 5

Input / output$1.8 / $9

Context1M

CachingRead + write

Best forOpus-class coding and agent performance at a balanced Sonnet rate for everyday production traffic.

Claude Model Family

Same API key and balance — switch tiers without changing your integration.

Compare all Claude models

Claude Fable 5.1

Anthropic’s most capable model, the Fable tier above Opus, for work where Opus 5.5 at high effort still falls short.

View model

Claude Opus 5

The previous Opus flagship, still available for workloads already validated on it; compare it against Opus 5.5 at your chosen effort.

View model

Claude Sonnet 5

A more balanced route for everyday coding, high-volume agents, and latency-sensitive production traffic.

View model

Other text models on EvoLink besides Claude Opus 5.5

GPT-5.6

OpenAI’s tiered frontier family for routing across capability, latency, and cost.

View model

Grok 4.5

xAI’s reasoning and tool-use route with a 500K context window and server-side search tools.

View model

Kimi K3

A long-context reasoning model for repository-scale coding and multi-document work.

View model

Gemini 3.6 Flash

A fast, low-cost route for production traffic that does not need Opus-tier judgment.

View model

Claude Opus 5.5 guides and related reading

Claude Opus 5 API Guide

First requests, effort, and the production checklist for the previous Opus model — most of it carries over, except that Opus 5.5 cannot disable thinking.

Read guide

Claude Opus 5 vs Claude Fable 5

The Opus-versus-Fable tier decision: when an Opus route is the right premium default and when Fable can justify a higher token price.

Read guide

Claude API Pricing Guide

How input, output, cache write, cache read, and tool charges add up across the Claude family.

Read guide

Claude Opus 6 Release Watch

Track the next Opus generation without treating its release date, API access, model ID, or pricing as confirmed.

Read guide

Claude Opus 5.5 API FAQ

Is the Claude Opus 5.5 API available through EvoLink?

Yes. Claude Opus 5.5 is available on EvoLink as a production route under model ID "claude-opus-5-5".

What model ID should I use for the Claude Opus 5.5 API?

Send model "claude-opus-5-5". The same ID works for both the OpenAI-compatible Chat Completions endpoint and the Anthropic Messages endpoint.

How much does the Claude Opus 5.5 API cost on EvoLink?

EvoLink pricing: $3.800 per 1M input tokens and $19.000 per 1M output tokens, against Anthropic’s $4.000 and $20.000.

Is Claude Opus 5.5 cheaper than Claude Opus 5?

Per token, yes: Anthropic lists Opus 5.5 about 20% below Opus 5 on input and output and about 60% below it on cache reads. Anthropic also reports it often completes the same task with fewer tokens, so compare cost per accepted task on your own workload.

How is Claude Opus 5.5 prompt caching billed?

5-minute cache writes cost $4.750 per 1M tokens and cache reads cost $0.192 on EvoLink, compared with Anthropic’s $5.000 and $0.200. They are metered separately. Use the displayed rates, including rounding, to estimate your workload.

How is the Claude Opus 5.5 web search tool billed?

Web search is charged per search at $0.010. Tokens the search results add to the request are billed normally.

Can I turn thinking off on Claude Opus 5.5?

No. Thinking is always on. Anthropic rejects thinking: disabled and budget_tokens; EvoLink converts legacy settings to adaptive thinking without disabling it. Omit thinking or send adaptive, and use effort (low, medium, high, xhigh, max; default medium) to control depth, latency, and cost.

What changes when I migrate from Claude Opus 5?

Change the model ID, remove thinking-off settings, and set effort explicitly: the default changes from high to medium. Forced tool choice is unsupported in both protocols (Messages any/tool; Chat Completions required/named functions). Use auto and validate tool calls. Read response blocks by type; context and max output are unchanged.

Which protocols and SDKs work with Claude Opus 5.5?

Use the OpenAI-compatible Chat Completions endpoint or the Anthropic Messages endpoint with the same EvoLink API key. Claude Code and other Anthropic-native clients work by pointing the base URL at EvoLink.

What context window and max output does Claude Opus 5.5 support?

The EvoLink route records a 1,000,000-token context window with up to 128K output tokens per response. Thinking counts toward max_tokens.

What should a production Claude Opus 5.5 evaluation measure?

Track first-pass success, accepted deliverables, retries, output tokens at your chosen effort, cache hit rate, valid tool calls, time to accepted result, human correction, and fallback rate — not the per-token rate alone.