Sonnet 5.5 at $2 and $10 per MTok direct vs a Sume agent turn

Anthropic's own page lists Sonnet 5.5 at **$2 per million input tokens and $10 per million output tokens**. On Sume, an agent turn on the same model is list x 1.25, then a 5.5% fee: **$2.6375 input and $13.1875 output**. That is the same 1.31875 multiplier as media jobs.

The four Anthropic models

Anthropic's page also shows the Opus and Haiku rows. Sume's list prices in the repo match them. Multiply by 1.25, then by 1.055, to get the agent-turn price.

A worked turn

Suppose an agent turn reads 100,000 uncached input tokens and writes 5,000 output tokens on Sonnet 5.5.

Direct: 0.1 x $2 + 0.005 x $10 = $0.25. On Sume: $0.25 x 1.31875 = $0.3296875. The $0.0796875 gap is what the 25% and the fee add.

Why an agent turn carries the fee

The 5.5% platform fee applies to all customer spend, including LLM turns. The base is the post-discount bill after the 1.25 step. Older constants in the repo describe some LLM models as having no Sume margin. The operations doc says that was superseded, and it is the document to trust.

What you get for the gap

An agent turn on Sume has its tools attached: generation, the sandbox, the files, and billing on one balance. A direct API call gives you tokens and nothing else. If you only need tokens, call the vendor. If the turn is going to fire a video job, one balance and one usage row per step is the reason to pay the multiplier.

Cache prices follow the same rule

Anthropic lists a 5-minute cache write at $2.50 per million tokens and a cache read at $0.20 on Sonnet 5.5. The same multiplier applies on Sume: a read is $0.20 x 1.31875 = $0.2637500 per million, and a write is $2.50 x 1.31875 = $3.296875.

Cache reads stay cheap in relative terms, because the ratio between a read and a fresh input token is unchanged. Long agent turns that re-read a large prompt benefit exactly as they do direct.

What to compare

Compare cost per finished task, not per token. A task that needs three tool calls, a sandbox and a video job is one balance on Sume. Done direct, it is an LLM bill, a sandbox bill and a video bill. The multiplier is the price of that consolidation, and you decide whether it is worth it for the workload.