Routing Preferences

Adjust how strongly a firerouter request favors its primary model or lower-cost models.

Routing preference controls how strongly a firerouter request favors its primary model or lower-cost models. Set it per HTTP request with x-routing-preference, or configure it for a supported harness with FireConnect.

Preference levels

Send an integer from 1 (strongest preference for the primary model) to 5 (strongest preference for lower-cost models):

Value	Name	Behavior
1	max-intelligence	Keep the turn on the primary model
2	more-intelligence	Lean toward the primary, compared with balanced
3	balanced	Default when the header is omitted
4	more-savings	Lean toward lower cost, compared with balanced
5	max-savings	Prefer the lower-cost models in the route

HTTP header

The HTTP header accepts only the integers 1 to 5. Names such as balanced are FireConnect CLI values, not HTTP header values.

Set the header on an API request:

curl https://api.fireworks.ai/inference/v1/chat/completions \
  -H "Authorization: Bearer $FIREWORKS_API_KEY" \
  -H "x-anthropic-api-key: $ANTHROPIC_API_KEY" \
  -H "x-routing-preference: 4" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "firerouter",
    "messages": [{"role": "user", "content": "Add a docstring to this function."}]
  }'

If the header is missing, invalid, or out of range, the router uses balanced behavior. It does not add a literal x-routing-preference: 3 header.

FireConnect

When you connect a harness to firerouter or a supported firerouter/... ID, pass --routing-preference with the connect command:

fireconnect claude --model firerouter --routing-preference 4
fireconnect opencode --model firerouter --routing-preference 2
fireconnect pi --model firerouter --routing-preference 5

Every harness can use any FireRouter ID. The table shows which IDs accept FireConnect’s --routing-preference flag:

Harness	IDs that accept --routing-preference
Claude Code	Bare firerouter only
OpenCode, Pi, VS Code	firerouter or any ID beginning with firerouter/
Codex, Cursor IDE, Copilot App, Copilot CLI, DeepSeek Harness	None

FireConnect accepts values 1 to 5 or the corresponding level names. In Claude Code, fireconnect claude --model firerouter/opus works, but adding --routing-preference to that ID returns an error: --routing-preference requires --model firerouter.

To set a preference where FireConnect does not support it, send the x-routing-preference header with manual setup, for example in ANTHROPIC_CUSTOM_HEADERS for Claude Code or http_headers for Codex. Cursor IDE and the Copilot App cannot send extra headers. Cursor CLI is not supported.

When to adjust

• High-volume workloads with many simple requests: try 4 or 5 so summaries, formatting, and straightforward Q&A are more likely to use a lower-cost model.
• Tasks where quality is critical (security review, complex reasoning, nuanced writing): try 1 or 2 so the router favors its primary model.
• Evaluating routing: start at 3 (balanced), then move one step at a time and compare cost and output quality.

Related

• FireRouter: firerouter, firerouter/opus, firerouter/astra, and firerouter/sol
• APIs and SDKs: HTTP headers and Provider Keys
• FireConnect: enable a router in a coding harness