GPT-6 Sol vs Claude Opus 5.5 for Coding: Price, Context, Agents — Which to Pick

Short answer

These are models in different weight classes, so "which is smarter" is the wrong question — the right one is "which for this task". GPT-6 Sol is OpenAI's mid-tier: $2 / $10 per million tokens at list, 272k context, native agent Codex CLI. Claude Opus 5.5 is Anthropic's flagship: $4 / $20 at list, 1M context, native agent Claude Code. On Moyi API both run on one key, at roughly $0.30 / $1.50 and $1 / $5 respectively as of the publish date. Below: the table and a scenario-based rule.

Side by side

Live prices are on the pricing page; the article shows publish-date values.

What the three big differences mean

Price: a bit over 3x

On the same session — 200k input and 20k output tokens — Sol on Moyi API costs about $0.09, Opus 5.5 about $0.30. For one task the gap is invisible; for a team running agents all day it is the difference between a $30 and a $100 weekly bill. So the question isn't "which model is better" but "on which tasks does the Opus premium pay for itself".

Context: 272k vs 1M

272k tokens is roughly 8–10k lines of code with docs; a million is 30–40k. If the job needs a whole monorepo or a long conversation history in context, Opus 5.5 does it without tricks, while on Sol you'd slice the context and lose cross-file links. If the project fits in 272k (most services do), the Opus advantage doesn't show up here.

Native agent

Codex CLI is designed around OpenAI models and the Responses API; Claude Code around Anthropic models and the Messages API. Through Moyi API you can call either model in either format, but the native agent-plus-model pair uses everything the tool offers (effort levels, subagents, system-prompt caching) without workarounds. If you already live in Codex, Sol is the natural pick; if in Claude Code, Opus 5.5.

Scenario-based rule

What most teams actually do is keep both: the cheap one as default, the expensive one on /model for the specific task. One Moyi API key covers both.

Switching between them with one key

Create the key in the console; the API host is the same for both models.

Codex CLI on Sol (~/.codex/config.toml):

model_provider = "teamorouter"
model = "gpt-6-sol"
[model_providers.teamorouter]
name = "Moyi API"
base_url = "https://api.moyiapi.com/v1"
env_key = "OPENAI_API_KEY"
wire_api = "responses"

Claude Code on Opus 5.5 (environment variables):

export ANTHROPIC_BASE_URL=https://api.moyiapi.com
export ANTHROPIC_AUTH_TOKEN="your Moyi API key"
export ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-5-5

Both from one script — in the OpenAI-compatible format only the model field changes:

from openai import OpenAI
client = OpenAI(base_url="https://api.moyiapi.com/v1", api_key="YOUR_KEY")

draft = client.chat.completions.create(model="gpt-6-sol", messages=[...])        # draft — cheap
review = client.chat.completions.create(model="claude-opus-5-5", messages=[...]) # review — expensive, but once

Step-by-step guides: GPT-6 Sol in Codex, Opus 5.5 in Claude Code.

Paying

Both models bill against one Moyi API balance, per token used. Card via Stripe or USDT; details in the billing FAQ.

FAQ

Can I run Opus 5.5 from Codex, or Sol from Claude Code? Technically yes through the gateway, but you lose the agent features designed around its native model. Simpler to keep the agent-plus-native-model pair and move tasks between agents.

What about GPT-6 Astra? That's OpenAI's flagship ($10 / $50), priced above Opus 5.5. If the task needs a top-tier model, the comparison is Astra vs Opus 5.5; Sol in that pair is the "several times cheaper for routine work" option.

Does caching work on both? Yes. The repeated part of a request (system instructions, the repo) is billed at the cache-read rate — several times cheaper than normal input on both. See the billing FAQ.

Are the request limits the same? No, they are set per model — rate limits page.

Next steps

• GPT-6 Sol via API
• Claude Opus 5.5 via API
• Create an API key — one for both models