tai/research/cap-protocol/openrouter-advisor-server-tool.md

OpenRouter: Advisor server tool

Metadata

Field	Value
Institute	Molodetz Institute — Research & Retrieval Division
Subject	cap-protocol
Document type	Source Dossier
Tier	1
Source title	OpenRouter: Advisor server tool
Source URL	https://openrouter.ai/blog/announcements/advisor-server-tool/
Source publisher / author	OpenRouter
Source type	blog post
Source date (published)	Unknown — not stated
Date researched	2026-10-25
Researched by	tai (agent), model: Claude Sonnet 5, on behalf of retoor
Research method	direct page fetch
Confidence	Medium
Status	Active

Summary

OpenRouter's cross-vendor advisor: any executor model can consult a stronger model mid-generation; the advice returns as a tool result and the executor writes the answer.

Key findings

• The advisor is 'a consultant, not a ghostwriter': single-turn, no nested tool loop; a tool-carrying sub-agent is a separate tool.
• Parameters: model, optional name, instructions, stream; the executor passes a prompt describing what it needs help with.
• Safeguards: an x-openrouter-advisor-depth header on inner calls and stripping the advisor tool from sub-calls prevent unbounded nesting; consultations are capped per request (number not given).
• Advisor tokens bill at the advisor model's own rates, shown separately from the executor's.
• Claimed use: the 10-20% of requests with architectural decisions or ambiguous edge cases; in a 50-tool-call session the article estimates maybe 2-3 consultations.

Pros / strengths

Names the safeguards a model-callable model needs: depth marker, tool stripping, per-request cap, separate billing.

Cons / limitations / caveats

Vendor announcement; the cap value and the 10-20% share are asserted, not measured; a search listing suggested other pages describe it as a sub-agent, so docs may differ.

Relevance to tai

Blueprint for tai's guard rails if a model-as-tool is added: nested calls get the tool removed, a static per-turn ceiling, and the cost line attributed to the consulted model.

Changelog

Date	Change
2026-10-25	Initial dossier created.