anthropic

Claude Sonnet 5

The other clean 5/5. Never fumbled a final answer, never over-searched, never mangled JSON.

5/5

benchmarks passed

$1.44

spent in total

tool calls

What it is.

Anthropic's latest Sonnet, tested via the first-party Claude API. The mid-tier of the Claude 5 line — below Opus on raw capability but tuned for agentic tool use and instruction-following.

What it does well.

Swept 5/5 with the least drama of any model in the suite — every run produced a clean, schema-conforming JSON object on the first try.
Knows when to stop. Averaged ~2.4 tool calls per benchmark; it gathered what it needed and answered instead of double-checking itself into a loop — the exact failure mode that sank the open-weights models on the Reddit task.
Passed the marketing-reddit benchmark (rank 5 tools by distinct-commenter mentions) that Nemotron and GLM both looped on and never concluded.

Where to be careful.

The priciest sweep here at standard Sonnet pricing ($3/$15 per MTok): $1.44 for the matrix — ~5.3x Mistral Large 3 and ~2.8x GLM 5.2, though still a fraction of Opus.
One operational gotcha: Sonnet 5 rejects the `temperature` parameter (like GPT-5 and the o-series). Send it and the API 400s and you get an empty response — you must drop `temperature`/`top_p` for this model.
Short-horizon agent tasks only (2-3 tool calls here). No data on long multi-hour chains or adversarial inputs.

Results by agent

Five real jobs.

SalesSales Research Analyst

Get financials on a company

Passed

Find Hightouch on Crunchbase and return their total funding, last round type, and a one-line description.

✓ 3 tool calls, $0.163. Cheapest of its five passes — found the Crunchbase org and verified the funding without redundant scraping.

MarketingMarketing Research Analyst

Find what customers are recommending on Reddit

Passed

Read a real r/sales thread on enrichment tools and rank the top 5 by how many people recommended them.

✓ 2 tool calls, $0.424. Committed to one thread, ranked Apollo top at 13 mentions, and stopped — the discipline the open-weights models lacked here.

CXCustomer Insights Analyst

Find what customers are complaining about

Passed

Pull Google Shopping reviews for AirPods Pro 2 (USB-C) and return the top 3 recurring complaints, with verbatim quotes.

✓ 2 tool calls, $0.374. One search, one review pull, clean complaint extraction with quotes.

CodingSenior Engineer Assistant

Read API docs and write working code

Passed

Read Stripe's official docs and write a real, working webhook-verification function in TypeScript.

✓ 3 tool calls, $0.347. Idiomatic HMAC-SHA256 verifier with `timingSafeEqual`, cited the Stripe docs, schema-clean.

Web ScrapingSales Outreach Specialist

Scrape a competitor's pricing page

Passed

Scrape Apollo.io's pricing page and return every tier (Free, Basic, Professional, Organization) with name, price, and top 3 features.

✓ 2 tool calls, $0.132. All four Apollo tiers with three features each.

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