Transparency

Claude Code System Prompt & Pricing

DeRouter forwards your requests as an authentic Claude Code client. This page documents exactly what is added to every request and how it is billed — so there are no surprises on your invoice.

Why this exists

Upstream providers expect their official clients to send a specific system prompt, client identity, and tool set. DeRouter sends your traffic under the Claude Code identity to keep upstream accounts compliant and stable. We mirror what your client already sends and add only the identity essentials on top — never content generated from, or influenced by, your conversation.

What is added

DeRouter does not inject a system prompt or tools of its own. It forwards your request under the Claude Code identity — your system prompt, your tools, unchanged. The only constant we add is the ~140-character identity core (client header + "You are Claude Code…" banner).

What that means for your request

Your request	What DeRouter adds	Added overhead
Full Claude Code CLI (system + tools)	Nothing — forwarded as-is	~0 (your own fingerprint)
No system prompt, no tools	Identity core only	~140 chars
Your own tools (no / short system)	Identity core + your tools, kept	Your tools only

For reference, a full Claude Code request carries the fingerprint below. DeRouter forwards this when you send it — it does not generate it for you.

Part	Content	Size
Client header	Client identity / billing header	~80 chars
Identity banner	"You are Claude Code…"	57 chars
System prompt	Claude Code CLI instructions (full text below)	~6,500 tokens
Tools	27 built-in CLI tool definitions	~24,000 tokens
Total per request		~30,000 tokens

The header and banner are the fingerprint core and are always present. The system prompt and tools are mirrored from your request, not padded.

Identity banner

You are Claude Code, Anthropic's official CLI for Claude.

Tools (27 built-in)

The standard Claude Code CLI tool set (~24,000 tokens of JSON schemas):

AgentAskUserQuestionBashCronCreateCronDeleteCronListEditEnterPlanModeEnterWorktreeExitPlanModeExitWorktreeGlobGrepNotebookEditReadScheduleWakeupSkillTaskCreateTaskGetTaskListTaskOutputTaskStopTaskUpdateWebFetchWebSearchWorkflowWrite

System prompt (full text)

The complete Claude Code CLI system prompt (~6,500 tokens):

How it is billed

The added content carries a 1-hour prompt cache, and DeRouter handles all of the caching for you — you don't configure anything.

1st requestWritten to cache once (one-time, full price)

within 1hServed from cache — billed at 10% of the base input rate

idle > 1hRe-written once on the next request

Your usage pattern	Cost of the added content
First request in a conversation	One-time cache write (up to ~30k for a full Claude Code request; far less for a minimal one)
Continued conversation (within 1h)	10% of base rate (cache read)
Long conversations	Amortized to near zero

Cache creation, renewal, and routing are all handled automatically. You don't need to do anything to benefit from this.

Questions about billing? Reach out any time.

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