Claude Opus 4.7 Migration | 3 Breaking Points from 4.6 and How to Fix Them

3 Places Where You Get Stuck from 4.6 (Guaranteed 400 Errors) + 2 Additional Notes

All 3 guaranteed breaking points in Opus 4.6 → 4.7 are breaking changes that return HTTP 400. The remaining 2 (tokenizer change and Thinking omission) are silent changes that cause quality degradation or cost increases source.

Breaking Point 1/3: Sampling Parameters Removed — 400 Error from temperature / top_p / top_k

Setting temperature, top_p, or top_k to any non-default value will return HTTP 400 source.

How to fix: Remove these parameters entirely from your request payload. To control output behavior, use system prompts as an alternative. Note that temperature = 0 has never guaranteed identical output.

How to find affected code:

# Example: find affected locations in your codebase
grep -rn "temperature\|top_p\|top_k" ./src/

Breaking Point 2/3: Extended Thinking Budget Removed — 400 Error if budget_tokens Remains

Specifying thinking: {"type": "enabled", "budget_tokens": N} will return HTTP 400 source. Adaptive Thinking is the only supported thinking mode in Opus 4.7.

Adaptive Thinking is off by default. If you want to use the thinking feature, explicitly set thinking: {type: "adaptive"}.

# Before (Opus 4.6)
thinking = {"type": "enabled", "budget_tokens": 32000}

# After (Opus 4.7)
thinking = {"type": "adaptive"}
output_config = {"effort": "high"}

Breaking Point 3/3: Assistant Message Prefill Removed — Merged into 400 Error (See Below)

The third breaking point is the removal of assistant message prefill. Details are in [Additional Note 1] in this section. The alternative is structured output or system prompts source.

Additional Note 1: Thinking Content Omitted by Default — Silent Change, Watch for UX Degradation

In Opus 4.7, thinking content is omitted by default (the default for display has changed to "omitted"). No error is thrown, but products that stream reasoning output may experience long silent gaps before text begins source.

If you want to show reasoning to users, explicitly set display: "summarized":

thinking = {
    "type": "adaptive",
    "display": "summarized",  # defaults to "omitted" if not set
}

Additional Note 2: Tokenizer Change — Up to 1.35× Token Consumption for the Same Text

Opus 4.7 uses a new tokenizer, which may consume up to approximately 35% more tokens for the same input text compared to Opus 4.6 (ranging from 1.0× to 1.35× depending on content type) source.

• It is recommended to update max_tokens to a value with more headroom.
• For workloads including image processing: token consumption per image may also increase up to approximately 3× due to high-resolution support.
• Measure actual consumption with the /v1/messages/count_tokens endpoint.

Breaking Point 3/3 Details: Assistant Message Prefill Removed — 400 Error, Use Structured Output or System Prompts

As a cumulative change from Opus 4.6, assistant message prefill now returns a 400 error. Use structured output (Structured Outputs) or system prompts as alternatives source.

Code Diff Examples — Understand 5 Lines to Rewrite via Before / After

Python SDK — Remove temperature / top_p / budget_tokens → Adaptive + effort

Key points for this section:

import anthropic

client = anthropic.Anthropic()

# =====================================================
# Before: Opus 4.6
# =====================================================
response = client.messages.create(
    model="claude-opus-4-6",
    max_tokens=64000,
    temperature=0.7,           # deprecated → remove
    top_p=0.9,                 # deprecated → remove
    thinking={
        "type": "enabled",
        "budget_tokens": 32000  # deprecated → change to Adaptive Thinking
    },
    messages=[{"role": "user", "content": "Please review this code."}],
)

# =====================================================
# After: Opus 4.7
# =====================================================
response = client.messages.create(
    model="claude-opus-4-7",   # update model ID
    max_tokens=64000,
    # temperature / top_p / top_k are removed
    thinking={"type": "adaptive"},          # Adaptive Thinking
    output_config={"effort": "high"},       # specify effort level
    messages=[{"role": "user", "content": "Please review this code."}],
)

If you want to show thinking content to users:

# When displaying Thinking content to users
response = client.messages.create(
    model="claude-opus-4-7",
    max_tokens=64000,
    thinking={
        "type": "adaptive",
        "display": "summarized",  # explicitly enable
    },
    output_config={"effort": "high"},
    messages=[{"role": "user", "content": "Please solve a problem requiring complex reasoning."}],
)

TypeScript SDK — Same 5-Line Rewrite as Python (Use as any to Work Around Unrecognized Fields)

Key points for this section:

import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic();

// =====================================================
// Before: Opus 4.6
// =====================================================
const responseBefore = await client.messages.create({
  model: "claude-opus-4-6",
  max_tokens: 64000,
  temperature: 0.7,          // deprecated → remove
  top_p: 0.9,                // deprecated → remove
  thinking: {
    type: "enabled",
    budget_tokens: 32000,    // deprecated → change to Adaptive Thinking
  },
  messages: [{ role: "user", content: "Please review this code." }],
} as any);

// =====================================================
// After: Opus 4.7
// =====================================================
const responseAfter = await client.messages.create({
  model: "claude-opus-4-7",   // update model ID
  max_tokens: 64000,
  // temperature / top_p / top_k are removed
  thinking: { type: "adaptive" },           // Adaptive Thinking
  output_config: { effort: "high" },        // specify effort level
  messages: [{ role: "user", content: "Please review this code." }],
} as any);

Operational Notes — Opus 4.6 Retirement Unannounced, Pricing Unchanged, Token Measurement Required

Opus 4.6 End-of-Support Notice — Retirement Schedule Not Announced (as of 2026-04)

As of now, Anthropic has not announced a retirement schedule for Opus 4.6. Check the Anthropic model deprecations page for official deprecation information.

For reference: Claude Sonnet 4 and Claude Opus 4 (both 20250514 snapshots) are scheduled for retirement on June 15, 2026 source.

Cost Comparison — 4.6 and 4.7 Have Identical Unit Pricing ($5/$25 per MTok), Token Consumption Up to 35% Higher

Key points for this section:

There is no price change from Opus 4.6 source. For the latest and most accurate pricing, see source.

Note: Due to the tokenizer change, token consumption may increase even for the same input (up to 35% more). It is recommended to measure actual costs against representative workloads before moving to production.

When to Use the xhigh Effort Level — Officially Recommended to Start with xhigh for Coding and Agent Use Cases

The xhigh effort level newly added in Opus 4.7 is the optimal setting for coding and agent use cases source.

Source: source When using xhigh or max, it is recommended to set max_tokens to at least 64,000 tokens source.

The specific token consumption multiplier when using xhigh varies by workload and task complexity. Measure with your actual workload before going to production.

Migration Checklist (Save This) — 6 Required Items + 8 Recommended Items + Validation

Copy and use as needed.

6 Required Items — Model ID / temperature / top_p / top_k / budget_tokens / prefill

Key points for this section:

• Change model ID from claude-opus-4-6 → claude-opus-4-7
• Remove temperature from the request
• Remove top_p from the request
• Remove top_k from the request
• Remove thinking: {type: "enabled", budget_tokens: N}

→ Replace with: thinking: {type: "adaptive"} + output_config: {effort: "high"}

• Remove assistant message prefill

→ Replace with: structured output or system prompts

8 Recommended Items — Increase max_tokens / Restore display / Estimate Image Costs / Evaluate xhigh / etc.

Key points for this section:

• Update max_tokens to a value with more headroom (for tokenizer change)
• Where reasoning content is displayed: add thinking.display = "summarized"
• Workloads handling images: update cost estimates for high-resolution support (up to ~3×)
• Coding and agent use cases: evaluate with effort set to "xhigh"
• Agent loops: consider adopting Task Budgets (beta)
• Client-side token estimation code: re-measure and recalibrate for Opus 4.7
• Coordinate conversion code: remove scale factor conversion (now 1:1 pixel mapping)
• Cybersecurity-related tasks: apply to the Cyber Verification Program

Validation — Benchmark Representative Workloads and Always Measure Before Going to Production

Key points for this section:

• Re-measure end-to-end cost and latency
• Re-evaluate output style (tone, length, and reaction patterns)
• Verify tool call frequency in agent workflows
• Check the format of progress messages in long-running agents

Sources (Primary Information)

• source — Details on new features and breaking changes
• source — Official migration guide (includes checklist)
• source — Adaptive Thinking API spec and code examples
• source — Effort level configuration
• source — Model list and pricing (referenced: 2026-04-23)
• source — Model retirement schedule
• Anthropic: Pricing — Latest pricing (referenced: 2026-04-23)