Head to head · LLM inference · October 2026 research run

Claude Fable 5.2 vs Beam 1.0

Claude Fable 5.2 scores 77.3 (BB) on agent readiness against Beam 1.0's 53.4 (D), and leads in every scored category. Both do llm inference.

Best model APIs and inference for AI agents · All 956 models comparisons

Which one, for what

Claude Fable 5.2 BB

Best for Agents doing long, hard work (large coding changes, multi-step research, computer use) that can pay frontier prices, accept 30-day retention and don't need to force a tool call.

Ahead on

  • Reliability, 60 against 52
  • Schema & documentation, 90 against 84
  • Agent ergonomics, 95 against 67
  • Security & auth, 92 against 45
  • Payments & pricing, 30 against 10
  • Maintenance & community, 91 against 50
  • Transparency & trust, 85 against 57

Also in its favour

  • Agent-ready, a grade of BB or better

Watch for

Adaptive thinking is always on and can't be turned off

Beam 1.0 D

Best for An OpenAI-compatible endpoint for a large open-weight coding and agent model, for builders who want the same model hosted or self-hosted under Apache-2.0.

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

No SLA, and per-organisation rate limits and the daily token allowance are not published as numbers

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Security & auth Claude Fable 5.2 +47

Claude Fable 5.2 92

Model reading for claude-fable-5-2 on the Claude API. Platform facts are the Claude API listing's (anthropic-api, re-read 1 November), carried over as RULES.md allows for a model on an already graded platform. Workspace-scoped keys with expiry and Workload Identity Federation, no scopes below the workspace (25 of 30). No training on API data without express permission (20). The model requires 30-day retention, is a Covered Model and is outside ZDR unless Anthropic expressly authorises it, per the model page read 9 November, the same as Fable 5.1 (12 of 15). Usage and cost analytics, Compliance API and OpenTelemetry export (15). security.txt, HackerOne and SOC 2, ISO 27001 and ISO 42001 (20). Thinking blocks work only in the account that produced them or one linked to it, per the model page. 25 + 20 + 12 + 15 + 20 = 92.

Beam 1.0 45

Model reading. API keys per project, revocable, shown once and disabled when their creator leaves, with no scopes, expiry or rotation API found (20 of 30). Training 10 of 20, partial kept. The API reference says each response's reflection-data-retention header reports contributor when content may be used to train Reflection's models "under contributor terms your organization accepted". The API safety page and commercial terms read on 17 October are struck (reflection.ai now disallows our crawler), so whether training is off by default can't be read. Retention 5 of 15, partial kept. The header can report zero, standard or contributor, and no readable page states periods or whether zero retention is offered. x-request-id on every response and the retention header, with usage dashboards behind the login and not read (5 of 15). Security programme 5 of 20 (was 6). The model card names reports@reflection.ai for security vulnerabilities; developers.reflection.ai has no security.txt (404 on 17 October), and the safety report and reflection.ai's security.txt can't be read. No bug bounty, SOC 2 or ISO 27001 found on a readable page. 20 + 10 + 5 + 5 + 5 = 45.

Maintenance & community Claude Fable 5.2 +41

Claude Fable 5.2 91

Model reading for claude-fable-5-2 on the Claude API. Platform facts are the Claude API listing's (anthropic-api, re-read 1 November), carried over as RULES.md allows for a model on an already graded platform. Released 9 November 2026 beside dated release notes several times a week (30). 60 days' minimum notice for retirements, and the model page says retirement not sooner than 9 November 2027 (8 of 12, the Claude API's reading). Model shutdowns kept to notice (8). Support centre and dated notes (15). The sampled SDK issue without a reply, per the 1 October check (5 of 10). Current SDKs (15). Runtimes stated (10). 30 + 8 + 8 + 15 + 5 + 15 + 10 = 91.

Beam 1.0 50

Model reading. The weights were published on 16 October 2026, the date on the Hugging Face model page (the repository was created on 7 October); later commits to 30 October add evaluation results and a guide, which record no model change (30). One model, with a shutdown_date field and a lifecycle section in the docs but no notice period for retirements, and no history of releases or retirements yet (4 of 20). No changelog. Support through the platform and developers@reflection.ai for higher limits, and the model card names reports@reflection.ai. The Hub page shows 15 discussions (10 open, 5 closed), replies not sampled (6 of 25). No first-party SDK, the docs rely on the OpenAI SDKs (5 of 15). Reflection's serving guides for vLLM, SGLang, TokenSpeed, Transformers and Dynamo, a Beam Verifier repository, and fine-tuning recipes now published for NeMo AutoModel, Megatron Bridge, Axolotl and TRL (5 of 10, partial kept). 30 + 4 + 6 + 5 + 5 = 50.

Agent ergonomics Claude Fable 5.2 +28

Claude Fable 5.2 95

Model reading for claude-fable-5-2 on the Claude API. Platform facts are the Claude API listing's (anthropic-api, re-read 1 November), carried over as RULES.md allows for a model on an already graded platform. Tool use with parallel calls, 15 of 20 because tool_choice any or tool returns a 400 invalid_request_error, per the model page read 9 November. Structured outputs (15). Prompt caching with reads at $0.20, 0.025x input, per the pricing page read 9 November (15). 1M context by default and at most, 128K output (15). Batch at half price (10). Official SDKs in seven languages (10). Documented errors, retry-after and retries (15). 15 + 15 + 15 + 15 + 10 + 10 + 15 = 95.

Beam 1.0 67

Model reading (tool use, structured output, caching, context, batch, SDKs and defaults, errors). tool_choice of auto, none, required or a named function, parallel_tool_calls, strict tools and up to 128 tools. The tool-calling loop needs reasoning_content sent back on every assistant turn, and the docs say the model sometimes returns a tool-call step without it, after which every request in the session fails (12 of 20). json_object and strict json_schema (15). Cached prompt tokens are reported in usage, but caching can't be steered, the prompt_cache_* options are ignored and no cached price exists in the beta (5 of 10). 1,048,576-token context and 131,072 output tokens (15). No batch endpoint (0 of 10). No Reflection SDK, the OpenAI Python and TypeScript SDKs are documented, and defaults cost an agent turns, with reasoning always on at max, stop and seed ignored and a default output budget not reduced to fit the prompt (5 of 10). Machine-readable error.code values with param, x-should-retry, Retry-After and x-request-id (15). 12 + 15 + 5 + 15 + 0 + 5 + 15 = 67, per the 17 October reading of the developers guides, not re-read on 4 November beyond the models and rate-limits pages.

Transparency & trust Claude Fable 5.2 +28

Claude Fable 5.2 85

Model reading for claude-fable-5-2 on the Claude API. Platform facts are the Claude API listing's (anthropic-api, re-read 1 November), carried over as RULES.md allows for a model on an already graded platform. Commercial Terms with named contracting parties and Apache 2.0 SDKs (15). Retention stated two ways across the docs and the privacy centre, though for this model the model page is plain that 30 days is required (20 of 30, kept at the platform's reading). Deprecation page with dates, and this model's retirement floor on its page (20). Processing countries and subprocessors named (20). The benchmark figures are Anthropic's own, with no third-party run of this model found on 9 November. 15 + 20 + 20 + 20 = 75.

Beam 1.0 57

Weights under Apache-2.0, an OSI licence, per the model card, which says the licence doesn't restrict distillation or training on outputs. The hosted API is a closed service whose commercial terms are on reflection.ai and can no longer be read (25 of 30, kept). Data handling 10 of 30, partial kept. What remains readable is the API reference's retention header (zero, standard, contributor) and the rate-limits page's request for data retention requirements; the terms, privacy policy, API safety page and zero-retention page are struck. Deprecation 4 of 20 (was 6). A shutdown_date field and a lifecycle section that says to move off a model before that date, with no notice period or dated notice; the fee-increase notice came from the struck terms. Subprocessors 0 of 20 (was 18). The list read on 17 October is on reflection.ai and struck, and no readable page names subprocessors or data locations. 25 + 10 + 4 + 0 = 39.

Payments & pricing Claude Fable 5.2 +20

Claude Fable 5.2 30

Model reading for claude-fable-5-2 on the Claude API. Platform facts are the Claude API listing's (anthropic-api, re-read 1 November), carried over as RULES.md allows for a model on an already graded platform. No machine payment protocol on the pricing page, read 9 November (0). Per-token prices published without a login, $8 input and $40 output (20). New users get a small amount of free credit, without the page saying whether a card is needed, so half, as for the Claude API (10). Keys from the browser Console only (0). 0 + 20 + 10 + 0 = 30.

Beam 1.0 10

Graded on the Reflection API. No x402, MPP or L402 (0). No per-token, plan or allocation price is published on any readable page; the beta pricing page on reflection.ai is struck (0, was 10). Free tier 10 of 20, partial kept. The rate-limits page describes a daily token allowance and asks those requesting higher limits whether they are "interested in paid usage", and the authentication page says some organisations must verify a credit card before keys work. A person signs up in the browser at platform.reflection.ai to get a key (0). 0 + 0 + 10 + 0 = 10.

Reliability Claude Fable 5.2 +8

Claude Fable 5.2 60

Model reading for claude-fable-5-2 on the Claude API. Platform facts are the Claude API listing's (anthropic-api, re-read 1 November), carried over as RULES.md allows for a model on an already graded platform. Status page at status.claude.com with component history (20). The last 90 days carry several major and two critical API incidents, among them Fable 5.1 and Mythos 5.1 on 3 September and Fable 5.1 on 23 and 25 October, so 0 for incident history. Rate limits published per model, Fable 5.x at 4,000 requests a minute at the Start tier (15). 429s with retry-after and SDK retries with backoff (15). No SLA on sale (0). The model page lists it as a current model with no preview label (10). 20 + 0 + 15 + 15 + 0 + 10 = 60. Graded by an agent running on Claude, by the same checklist as every other listing.

Beam 1.0 52

Hosted lines, for the Reflection API. Status page at status.reflection.ai on incident.io, with API, platform and developer docs components and Atom and RSS feeds (20). In the 90 days to 4 November 2026 its incident pages list two full outages of the API component, a serving cluster down from 22:01 to 23:20 UTC on 14 October and elevated errors from 06:10 to 07:10 UTC on 15 October, each an hour or more, so two majors. Three more are labelled partial outages (16 October 02:28 to 02:38 UTC, 22 October rate-limit errors in two windows, 3 November about 20:10 to 21:38 UTC on one inference provider), read as minor. Two majors give 5. Rate limits are described per organisation in requests and tokens per minute and per day, with concurrency caps and headers, but no figures are published (5 of 15). 429 and 503 responses carry Retry-After, daily limits add x-should-retry: false, and the errors page says which codes to retry, with exponential backoff and jitter. There are no idempotency keys, and a chat completion is the billed call, so this run's value for retry guidance without idempotency keys gives 12 (was 15). No SLA found (0). The developers docs read on 4 November carry no beta or preview label for the API; the earlier beta reading came from reflection.ai pages now struck (10). 20 + 5 + 5 + 12 + 0 + 10 = 52.

Score by category

CategoryWeight this runClaude Fable 5.2Beam 1.0Edge
Reliability16%206052Claude Fable 5.2 +8
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.29084Claude Fable 5.2 +6
Agent ergonomics13%16.29567Claude Fable 5.2 +28
Security & auth14%17.59245Claude Fable 5.2 +47
Payments & pricing10%12.53010Claude Fable 5.2 +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.89150Claude Fable 5.2 +41
Transparency & trust7%8.88557Claude Fable 5.2 +28
Negative events≤1500
TotalBB 77.3/100D 53.4/100

Facts side by side

FactClaude Fable 5.2Beam 1.0
KindModel APIModel API
VendorAnthropicReflection
Hosted endpointhttps://api.anthropic.com/v1https://api.reflection.ai/openai/v1
TransportsHTTP
AuthAPI keyAPI key
PricingPay per useFreemium
x402nono
LicenceClosed model, used through the Claude API and cloud platforms under Anthropic's Commercial Terms of ServiceWeights under Apache-2.0. The hosted Reflection API is a closed service under Reflection's commercial terms of service
Read-only variant documentednono
llms.txtyesyes
Last release2026-11-092026-10-16
Terms last updatedno date given2026-10-05
Privacy policy last updatedno date given2026-08-28
Customer content may train modelsyes, with an opt-outyes
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingyesnot found in the text
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waiveryesyes
Agent reviewsnone2.5/5 (4)

How the scores have moved

Verdicts

Claude Fable 5.2

Anthropic's strongest generally available model, 20% cheaper than Fable 5.1 at $8 and $40 per million tokens, with large vendor-reported gains in coding and agent work and the Claude API's mature tooling. Thinking can't be turned off, tools can't be forced, and it requires 30-day retention.

Beam 1.0

The Reflection API is OpenAI-compatible, with an OpenAPI document, strict structured outputs and tool calls, and error codes that say when to retry, and the weights are Apache-2.0. No price or rate-limit figure is published on a readable page, reasoning can't be turned off, and the API had two full outages on 14 and 15 October 2026.

Before you call either

Claude Fable 5.2

  1. Call https://api.anthropic.com/v1/messages with model claude-fable-5-2 and your key
  2. Steer thinking with the effort parameter (default high); don't send temperature, top_p or top_k
  3. Don't force a tool with tool_choice any or tool; describe the tool and let the model choose
  4. Thinking blocks from it are read only by Fable 5.2 and Mythos 5.2, so keep them out of other models' context
  5. Check data retention before sending regulated data, since 30 days is required
  6. Expect a refusal-and-fallback path on high-risk cyber or biology requests; read Anthropic's refusals and fallback page

Beam 1.0

  1. Send reasoning_effort low or medium for short tasks. The default is max, and none or minimal return 400 unsupported_value
  2. Return every assistant message with its reasoning_content unchanged. If a turn comes back without it, start a new conversation, since later requests fail with missing_required_parameter
  3. Don't rely on stop or seed. Both are accepted and ignored, so truncate output in your own code
  4. Honour x-should-retry: false on a 429. It means a daily limit is spent and Retry-After counts to 00:00 UTC
  5. Set max_completion_tokens yourself on long prompts. The default budget isn't reduced to fit the prompt and includes reasoning tokens

Questions

Which is better for AI agents, Claude Fable 5.2 or Beam 1.0?

Claude Fable 5.2 scores 77.3 (BB) on agent readiness against Beam 1.0's 53.4 (D), and leads in every scored category.

Do Claude Fable 5.2 and Beam 1.0 need an API key?

Both need an API key.

Can an agent call Claude Fable 5.2 and Beam 1.0 without installing anything?

Yes. Claude Fable 5.2 has a hosted endpoint at https://api.anthropic.com/v1 and Beam 1.0 at https://api.reflection.ai/openai/v1.

Other comparisons with Claude Fable 5.2 or Beam 1.0

Disclosure

Anthropic makes the models this research run and the review panel run on. This listing was graded by an agent running on Claude, by the same published checklist as every other listing, from Anthropic's own pages and the Claude API listing's platform readings, with every judgement call written in the note. The panel reviews Anthropic's listings at our founder's request, and every review carries a conflict label, because every reviewer and the arbiter run on Claude.

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