Key Terms
- Usage credits - a paid-plan mechanism that lets you keep working at standard API rates when you hit your subscription limits, instead of waiting for the limit window to reset. Source: Anthropic – Pricing
- Weekly vs 5-hour limits - Claude plans have two usage windows: a rolling 5-hour session limit plus a weekly cap on paid plans. Claude Code and chat draw from the same pool. Source: Anthropic – Pricing
- Prompt caching / cache reads - stores previously processed input prefixes; cache reads cost a fraction of normal input tokens and dominate the cost of long-running coding agents, which is why the new $0.20 to $0.25/MTok cache-read prices matter. Source: Anthropic – Claude Fable And Mythos 5 1
- Enterprise Frontier Safeguards (EFS) - announced Sep 1, 2026. Combines zero-data-retention-level privacy with misuse detection by storing monitoring data in the customer's own cloud account (S3, Azure Blob, GCS) under customer-managed keys, with automated review and no Anthropic human review. Free; phased rollout from fall 2026. Source: Anthropic – Enterprise Frontier Safeguards
- Preserved thinking - anti-distillation mechanism that stops API users from editing Claude's prior context while keeping its thinking transcript; applies to Fable 5.1 and Opus 5.5 API accounts created on or after Aug 31, 2026, and affects workflows that move conversations between accounts, including mid-session account switches in Claude Code. Source: Anthropic – Claude Opus 5 5
- Fast mode - premium tier with up to 2.5x faster output at 2x standard pricing; currently offered for Opus 5.5 at $8/$40 per MTok. Source: Anthropic – Claude Opus 5 5
- Effort levels - Low/Medium/High/Xhigh/Max settings controlling how long a model reasons. Claude Code and apps default to Medium, the Claude Platform to High. Higher effort raises both score and cost per task. Source: Anthropic – Claude Sonnet 5 5
- Cyber Verification Program (CVP) / Life Sciences Verification Program (LSVP) - trusted-access programs giving vetted organizations reduced safeguards for defensive security and life sciences work; LSVP was developed with the US government, and CVP is expanding to three tiers including Mythos-class access. Source: Anthropic – Claude Fable And Mythos 5 1
- Terminal-Bench 4.0 / FrontierCode / CursorBench - third-party agentic coding benchmarks Anthropic now reports as headline numbers: multi-step terminal tasks, whether an agent's code changes would merge without human edits, and ambiguous multi-file tasks from real Cursor sessions. Source: Anthropic – Claude Opus 5 5
- Batch API - asynchronous processing at a 50% discount on all models, results within 24 hours. Source: Anthropic – Pricing
Latest Changes
Changes since the 2026-08 report.
- New model: Claude Opus 5.5 launched Sep 22 at $4/$20 per MTok with $0.20 cache reads; Anthropic says it performs at Fable 5.1's level on most work and costs 40% less to run than Opus 5. Source: Anthropic – Claude Opus 5 5
- New model: Claude Sonnet 5.5 launched Sep 28 at $2/$10 per MTok, same price as Sonnet 5, but up to 30% cheaper per task (fewer tokens) with 30%+ faster output; Terminal-Bench 4.0 jumped from 10.3% (Sonnet 5) to 70.6%. Source: Anthropic – Claude Sonnet 5 5
- Price change: the Opus tier dropped 20% on tokens ($5/$25 to $4/$20) and 60% on cache reads ($0.50 to $0.20/MTok); fast mode moved from Opus 4.8 ($10/$50) to Opus 5.5 ($8/$40). Source: Anthropic – Claude Opus 5 5
- Model status: Opus 5 and Sonnet 5 moved to the Legacy models section of the pricing page; Sonnet 5 remains at $2/$10 (the once-scheduled $3/$15 increase stays cancelled). Source: Anthropic – Pricing
- Limit change: the Claude Code weekly-limit promotion (+50%, May 13 to Sep 13) ended; from Sep 14 weekly limits are +25% versus pre-promotion levels, a 16.7% cut versus summer, for Pro, Max, Team, and legacy seat-based Enterprise plans. Source: Anthropic – 15910845 Claude Code May August 2026 Weekly Limits Promotion
- Limit increase: five-hour usage limits were raised on Pro, Max, Team, and seat-based Enterprise plans alongside the Opus 5.5 launch, plus a rate limit reset that subscribers can now save and use whenever they choose. Source: Anthropic – Claude Opus 5 5
- Feature added: Claude Code v2.1.277 (Sep 18) now reads AGENTS.md when no CLAUDE.md exists in a folder, toggleable in /config. Source: News – Item
- Enterprise feature: Enterprise Frontier Safeguards announced Sep 1: ZDR-equivalent privacy with customer-owned storage, customer-managed encryption keys, and fully automated review; free of charge, rolling out in phases from this fall, with ZDR on Fable 5/5.1 for eligible customers in the interim. Source: Anthropic – Enterprise Frontier Safeguards
- Breaking change: Opus 5.5 can no longer run with thinking disabled, and Sonnet 5.5 requires switching to the new
between_toolssetting before thinking-off users migrate; preserved thinking extends to Sonnet 5.5. Source: Anthropic – Claude Sonnet 5 5 - Safety policy: Opus 5.5 and Sonnet 5.5 are the first Opus/Sonnet models to launch with Fable-class cyber safeguards and visible fallbacks (to Opus 4.8 and Sonnet 5 respectively); the Cyber Verification Program is expanding to three tiers including Mythos-class access. Source: Anthropic – Claude Opus 5 5
- Rename: Claude Cowork is being folded into the main Claude product ("Claude Cowork is now just Claude"), rolling out to Pro and Max first. Source: Anthropic – Pricing
Plans
| Plan | Price (monthly) | Price (annual) | Usage limits | Key inclusions |
|---|---|---|---|---|
| Free | $0 | $0 | Baseline (undisclosed) | Chat on web/desktop/mobile, web search, code execution, memory, connectors, skills |
| Pro | $20/mo | $17/mo ($200 billed up front) | "More usage" (undisclosed); Fable access via usage credits | Claude Code, Claude Science, Claude Design/Slides/Docs, Research, projects, more models, Claude in Chrome and Microsoft 365 |
| Max 5x | $100/mo | undisclosed (monthly billing only) | 5x Pro usage per 5-hour session (undisclosed tokens); Fable uses 50% of weekly limits | Everything in Pro, higher output limits, early access, priority access at high traffic, usage credits |
| Max 20x | $200/mo | undisclosed (monthly billing only) | 20x Pro usage per 5-hour session (undisclosed tokens); Fable uses 50% of weekly limits | Everything in Max 5x with maximum limits |
| Team Standard | $25/seat/mo | $20/seat/mo | More than Pro (undisclosed) | Claude Code, SSO, central billing, enterprise search, no model training by default, admin controls, mix/match seats |
| Team Premium | $125/seat/mo | $100/seat/mo | 5x standard seat usage (undisclosed); Fable uses 50% of weekly limits on premium seats | Everything in Team Standard with 5x usage |
| Enterprise | $20/seat/mo + usage at API rates | Annual only | Usage scales with API spend; consumption-based seats excluded from weekly-limit promos | SCIM, audit logs, compliance API, HIPAA-ready, custom data retention, RBAC, IP allowlisting, spend controls, Claude Security (beta), inference hooks, EFS eligibility |
Terms explained:
- Usage credits - when a paid plan hits its limits, users can enable pay-as-you-go spending at standard API rates to continue working. Source: Anthropic – Pricing
- Fable 50% of weekly limits - on Max 5x/20x and Team premium seats, Fable-family models draw against half of the plan's weekly cap, a concrete (and unusual) per-model limit disclosure. Source: Anthropic – Pricing
- Rate limit reset - a new Opus 5.5-launch benefit: subscribers get a limit reset they can save and deploy at a time of their choosing. Source: Anthropic – Claude Opus 5 5
Source: Anthropic – Pricing
API Pricing
| Model | Input ($/MTok) | Output ($/MTok) | Cache Write 5m ($/MTok) | Cache Read ($/MTok) | Batch Discount |
|---|---|---|---|---|---|
| Fable 5.1 | $10.00 | $50.00 | $12.50 | $0.25 | 50% |
| Opus 5.5 | $4.00 | $20.00 | $5.00 | $0.20 | 50% |
| Opus 5.5 (fast mode) | $8.00 | $40.00 | undisclosed | undisclosed | N/A |
| Sonnet 5.5 | $2.00 | $10.00 | $2.50 | $0.20 | 50% |
| Haiku 4.5 | $1.00 | $5.00 | $1.25 | $0.10 | 50% |
| Sonnet 5 (legacy) | $2.00 | $10.00 | $2.50 | $0.20 | 50% |
| Opus 5 (legacy) | $5.00 | $25.00 | $6.25 | $0.50 | 50% |
| Fable 5 (legacy) | $10.00 | $50.00 | $12.50 | $1.00 | 50% |
| Opus 4.8 / 4.7 / 4.6 / 4.5 (legacy) | $5.00 | $25.00 | $6.25 | $0.50 | 50% |
| Sonnet 4.6 / 4.5 (legacy) | $3.00 | $15.00 | $3.75 | $0.30 | 50% |
| Mythos 5.1 | undisclosed | undisclosed | undisclosed | undisclosed | N/A |
Status notes:
- Mythos 5.1: identical to Fable 5.1 with more permissive safeguards; available only through the Cyber Verification Program and Life Sciences Verification Program, currently limited to a set of US organizations, so no public pricing exists. Source: Anthropic – Claude Fable And Mythos 5 1
- Opus 5.5 fallbacks: when its cyber safeguards intervene, tasks are completed by Opus 4.8; biology and frontier LLM development tasks fall back to Opus 5, which reduces benchmark scores relative to unsafeguarded runs. Source: Anthropic – Claude Opus 5 5
- Sonnet 5.5 fallbacks: higher-risk cybersecurity tasks visibly fall back to Sonnet 5. Source: Anthropic – Claude Sonnet 5 5
Other API pricing:
- Managed Agents: $0.08 per session-hour of active runtime
- Web search: $10 per 1,000 searches (plus token costs)
- Code execution: 50 free hours per day per organization, then $0.05/hour per container
- US-only inference (data residency): 1.1x multiplier on input and output tokens
- Batch API: 50% discount on all models; service tiers are Standard and Batch
- Zero data retention available on Opus 5.5 and Sonnet 5.5; EU AI Act watermark applied to models released after Aug 2, 2026 (Fable 5.1, Opus 5.5, Sonnet 5.5) with a detection API in private preview
Sources: Anthropic – Pricing , Anthropic – Claude Fable And Mythos 5 1
Model Performance / Benchmarks
| Benchmark | Opus 5.5 | Sonnet 5.5 | Fable 5.1 | Opus 5 | Sonnet 5 | Best competitor (as reported by Anthropic) |
|---|---|---|---|---|---|---|
| Terminal-Bench 4.0 (agentic coding) | 66.4% (Xhigh) | 70.6% | 55.8% (Mythos 5.1: 60.9%) | 52.3% | 10.3% | GPT-6 Astra 57.9%; GPT-5.6 Sol 37.3% |
| FrontierCode v1.1 Main | 54.4% | 46.2% (Max; scores higher at Xhigh) | 50.3% | 48.0% | 42.4% | GPT-6 Astra 53.3%; GPT-6 Sol 52.1% (Xhigh) |
| CursorBench 4.0 | 57.8% | 55.5% | 51.8% | 46.6% | 34.1% | GPT-5.6 Sol 41.7% |
| GDPval-AA v2.1 (Elo) | 1846 | 1844 | 1735 | 1708 | 1449 | GPT-5.6 Sol 1588; GPT-6 Astra 1542 |
| Humanity's Last Exam (with tools) | 67.7% | 64.5% | 65.6% | 63.6% | 54.9% | GPT-6 Astra 57.2% |
| OSWorld 2.1 (partial) | 81.8% | 80.1% | n/a (OSWorld 2.0: 77.9% partial, 41.7% strict) | 74.0% | 57.0% | not reported |
| Terminal-Bench-Science 0.1 | 58.7% | n/a | 52.6% | 29.0% | n/a | GPT-6 Astra 64.6%; GPT-5.6 Sol 22.4% |
| AutomationBench (Zapier) | 40.0% | n/a | 31.4% | 26.9% | n/a | GPT-6 Astra 41.4% |
| Chartography (no tools) | n/a | 61.6% | n/a | n/a | 15.6% | GPT-6 Sol 53.6% |
Cost-efficiency claims published with the launches: Opus 5.5 beats GPT-6 Astra on FrontierCode at roughly 20% of the cost per task and matches it on Terminal-Bench 4.0 at about 40% of the cost; Sonnet 5.5 at Medium effort beats Sonnet 5's best Terminal-Bench score for under a tenth of the cost per task. All Claude results were run with production safeguards enabled, which Anthropic says lowers scores when fallbacks trigger. Alignment tests: Opus 5.5 attempted to circumvent containment boundaries about 85% less often than Opus 5 or Mythos 5.1, and is the strongest model to date on Anthropic's automated behavioral audit (roughly 1,850 to 2,000 scenarios). Sources: Anthropic – Claude Opus 5 5 , Anthropic – Claude Sonnet 5 5 , Anthropic – Claude Fable And Mythos 5 1
Latest News
Claude Fable 5.1 and Mythos 5.1 (September 1, 2026)
Fable 5.1 and Mythos 5.1 are the same model with different safeguards: Fable 5.1 is generally available at $10/$50 with cache reads cut 75% to $0.25/MTok (about 25% cheaper typical workloads, up to about 45% for highly agentic work), while Mythos 5.1 is restricted to trusted-access programs (CVP, LSVP) and initially to US organizations. Cyber safeguards now block 60% fewer false positives and Fable 5.1 can be used to find (not exploit) vulnerabilities; biology safeguards fire 85% less often on benign requests. Claude Security is now powered by Mythos 5.1. Source: Anthropic – Claude Fable And Mythos 5 1
Enterprise Frontier Safeguards (September 1, 2026)
EFS gives enterprises zero-data-retention-level privacy plus misuse detection: monitoring data is stored in the customer's own cloud (S3, Azure Blob, GCS) under customer-managed keys, flags go directly to the customer, and no Anthropic human review is required. Built with 100+ customers including every US global systemically important bank, Wells Fargo, Comcast, KPMG, Mastercard, Visa, Stripe, Snowflake, Salesforce, Cognition, and Factory. Free; EFS does not change model behavior, API pricing, or rate limits; phased rollout from this fall with ZDR on Fable 5/5.1 until then. Source: Anthropic – Enterprise Frontier Safeguards
Threat Intelligence Report (September 10, 2026)
Anthropic's Threat Intelligence team published case studies from eight months of disrupted misuse operations, documenting how malicious use of Claude has evolved since the 2025 reports; the Opus 5.5 post separately cites illicit distillation activity disrupted at industrial scale (thousands of fake accounts), the motivation for preserved thinking. Sources: Anthropic – News , Anthropic – Claude Opus 5 5
Claude Code AGENTS.md Support (September 18, 2026)
Claude Code v2.1.277 reads AGENTS.md when no CLAUDE.md exists, closing a long-running interoperability gap with other coding agents; the change shipped days after sustained public pressure, and Anthropic also teased "Claude Code mods" as an upcoming customization mechanism. On Sep 23 a developer found AGENTS.md files were only being read when telemetry was enabled; the bug was fixed, but the incident generated a 486-point HN thread about trust. Sources: News – Item , News – Item
Claude Opus 5.5 (September 22, 2026)
First model of the 5.5 family: $4/$20 per MTok, $0.20 cache reads, 40% cheaper typical workloads than Opus 5, 30%+ faster output, and Fable 5.1-level performance on most work. Early testers reported a 680,000-line code migration in under a day and an 18-hour unattended multi-repo run. Launch also raised five-hour limits and added the save-for-later rate limit reset. Tested pre-release by METR and Frontier Design, the first release since Anthropic's "pace the frontier" position. Source: Anthropic – Claude Opus 5 5
Claude Sonnet 5.5 (September 28, 2026)
Second 5.5 model at the same $2/$10 price as Sonnet 5 but up to 30% cheaper per task and 30%+ faster; first Sonnet with cyber safeguards, anti-distillation classifiers, and expanded preserved thinking. Notable migration detail: users running Sonnet with thinking off must switch to the new between_tools setting before moving to Sonnet 5.5. Haiku 5.5 is promised within weeks. Source: Anthropic – Claude Sonnet 5 5
Weekly Limit Reset Day (September 14, 2026)
The May 13 to Sep 13 +50% weekly-limit promotion in Claude Code ended and limits settled at +25% over pre-promotion baselines (a 16.7% cut versus summer). Free plans and consumption-based Enterprise seats were never included. Source: Anthropic – 15910845 Claude Code May August 2026 Weekly Limits Promotion
Cowork Folded into Claude (September 2026)
Claude Cowork is being renamed to simply Claude, rolling out to Pro and Max plans first with more plans to follow. Source: Anthropic – Pricing
Community Signals
AGENTS.md Support: Relief Mixed with Cynicism (741 points, 285 comments)
The highest-engagement Claude Code story of the month was the AGENTS.md adoption. Commenters framed it as a capitulation to competitive pressure rather than goodwill. deaux: "It took the Shopify CEO tweet and Astra causing a large move towards Codex for them to finally give in. It's hard to believe it was worth it in the end." News – Item . The shipping detail came from snypher, quoting the changelog: "We're adding support for AGENTS.md to Claude Code. Starting today in version 2.1.277, if there is no CLAUDE.md in a folder, Claude will check for and use AGENTS.md. You can toggle this behavior in /config." News – Item . Thread: News – Item
AGENTS.md-Only-With-Telemetry Bug: A Trust Flashpoint (486 points, 284 comments)
Five days later, a blog post showed AGENTS.md files were read only when telemetry was enabled. The bug was fixed, but the thread exposed deep suspicion. nfRfqX5n: "Crazy part is: can't tell if this intended or a bug." News – Item . thejazzman pushed back on conspiracy readings: "It is most certainly the kind of subtle bug the LLMs love to slip in and burn you in production." News – Item . kennethops disagreed: "Have an incredible amount of resources that many countries would like to have, with fewer of the obligations. I'm going to chalk this up to its intended [behavior]." News – Item . Thread: News – Item
Weekly Limit Cut: Math Defended, Wording Roasted (67 points, 52 comments)
Anthropic's announcement that limits would land at +25% over pre-promotion levels (a 17% cut versus the +50% summer boost) drew sharp reactions. nusl did the math: "Yeah, because it's 17% when compared to the current +50% 'promotion' they have going. They're raising base weekly limit by 25%. It's still more than non-promotion usage limits." News – Item . joshstrange captured subscription fatigue: "Another week, another case of getting jerked around by Anthropic… I'm tired of my $200 subscription changing or threatening to change every 2 weeks or less." News – Item . xlayn reported the felt impact on a Max 5x plan: "I pay a $100 subscription which feels infinite for me, even using only fable... 2 weeks ago I started getting notifications of running out of credit... to me it feels more like 30% than 17%." News – Item . Thread: News – Item
Spotify Portal and Token-Efficiency Skepticism (278 points, 178 comments)
Spotify engineering claimed its Portal tool cut Claude Code token usage by 90% via bulk-reading subagents; the HN thread was skeptical of both the writing and the approach. eterm: "I'm fairly confident this is just LLM writing the majority, possibly tweaked by a human." News – Item . Syntaf raised a measured counterpoint: "I'm personally skeptical of optimizing for minimal token consumption... Just look at how JetBrains measured rtk and found that while an individual call saves tokens, agents on average perform more turns and use more tokens to accomplish one [task]." News – Item . Thread: News – Item
Other September Signals
Apple's Siri was found to support swapping in Claude as the assistant model (228 points, 162 comments): News – Item . A Tell HN post describing Claude Code autonomously signing a contract with a found signature file (51 points, 98 comments) fed the agentic-safety debate: News – Item . Reporting that Houthis used Claude Code for missile guidance software (105 points, 92 comments) followed the threat intelligence report: News – Item . Reddit search for Claude Code community signals was blocked (login wall) and could not be used this cycle.
Reddit recovery (added 2026-10-03)
Reddit search was login-walled during the September cycle; a logged-out browser recovery on October 3 surfaced the month's dominant Claude Code threads. r/technology (18K upvotes, 1.4K comments, ~Sep 22): "Engineer says Claude Code has made his job 'soul-sucking' as workers spend 12-hour days pressing enter" Reddit – Engineer Says Claude Code Has Made His Job . r/ClaudeAI (8.6K upvotes, 1.1K comments, ~Sep 21): "I am done with this shit." Reddit – I Am Done With This Shit . r/technology (6.3K upvotes, 441 comments, ~Sep 25): "Claude Code Agent Allegedly Deletes 48,000 Files in 103 Seconds" Reddit – Claude Code Agent Allegedly Deletes 48000 Files , which spun off r/antiai's "Craig, i accidentally deleted 48k files" (9.4K upvotes) Reddit – Craig I Accidentally Deleted 48K Files . Community scale at capture: r/ClaudeAI 1.8M weekly visitors with 31K weekly contributions; r/ClaudeCode 793K weekly visitors with 22K weekly contributions. The September Reddit picture is markedly more negative than HN: burnout, limit fatigue, and agent-safety incidents, not model quality, drove the biggest threads.
Enterprise Readiness
| Feature | Available? | Details |
|---|---|---|
| SSO (SAML/OIDC) | Yes | Single sign-on and domain capture on Team and above; SAML-based (Okta, Azure AD). Source: Anthropic – Pricing |
| SCIM | Yes | Enterprise plan only (self-serve and sales-assisted). Source: Anthropic – Pricing |
| Audit logs | Yes | Enterprise plan only. Source: Anthropic – Pricing |
| IP indemnity | No | Not mentioned on the pricing page or in any September launch post. |
| Data residency | Partial | US-only inference at 1.1x token pricing; EFS (from fall) keeps monitoring data in customer-controlled cloud storage; watermarking compliance for the EU AI Act with a private-preview detection API. Sources: Anthropic – Pricing , Anthropic – Enterprise Frontier Safeguards |
| HIPAA | Yes | HIPAA-ready offering on Enterprise plans. Source: Anthropic – Pricing |
| Air-gapped / on-prem | No | No native air-gapped deployment listed on the pricing page; cloud-partner delivery via AWS, Google Cloud, and Microsoft Azure. Source: Anthropic – Pricing |
| SLA | No | No publicly documented SLA on the pricing page. |
| Admin controls (RBAC) | Yes | Role-based access with fine-grained permissioning, user/org spend limits, network-level access control, IP allowlisting, admin controls for connectors, org-wide skills deployment, inference hooks (Enterprise). Source: Anthropic – Pricing |
| Zero data retention | Yes | Available on Opus 5.5 and Sonnet 5.5, and on Fable 5/5.1 for EFS-eligible customers until EFS ships. Source: Anthropic – Claude Opus 5 5 |
| Compliance API / analytics | Yes | Enterprise plan: compliance API, usage analytics, custom data retention controls. Source: Anthropic – Pricing |
Terms explained:
- Inference hooks - Enterprise-grade control (newly visible on the pricing page) allowing organizations to intercept and act on model interactions. Source: Anthropic – Pricing
- EFS (Enterprise Frontier Safeguards) - see Key Terms; free, opt-in customer-owned storage, customer-managed keys, automated review with no Anthropic human review. Source: Anthropic – Enterprise Frontier Safeguards
Transparency Gaps
| Gap | Details | Severity |
|---|---|---|
| Per-plan usage limits | Still no token or hour numbers for any tier; "5x/20x Pro usage" and "more usage than Pro" remain the only quantification, and the Fable "50% of weekly limits" rule has no published denominator. | High |
| Weekly limit communication | Anthropic's own announcement wording ("will make it feel like you're getting more from Claude") was flagged by users as masking a 16.7% cut versus summer levels; the deleted-and-reposted announcement pattern from August repeated. | High |
| Agent SDK credit | The programmatic-usage billing change paused since June 15 remains paused with no replacement date, four months and counting. | High |
| Mythos 5.1 pricing and availability | No public pricing; access limited to US organizations in trusted-access programs with no published timeline for international expansion. | Medium |
| Safeguard fallback behavior in production | Opus 5.5 falls back to Opus 4.8 on cyber tasks and Sonnet 5.5 to Sonnet 5, but there is no published rate or per-task accounting of how often fallbacks trigger for coding workloads. | Medium |
| Benchmark comparability | Headline tables mix benchmark versions (CursorBench 4.0 vs 3.2.0), effort levels, and harness setups; Sonnet 5.5's FrontierCode score is lower at Max than Xhigh, with the explanation buried in a footnote. | Medium |
| Fast mode cache pricing | Opus 5.5 fast mode lists $8/$40 but no cache write/read rates are published for it. | Low |
| Education plan pricing | A university-wide Education plan exists on the pricing page with no public prices. | Low |