OpenRouter

OpenRouter is a multi-provider API and routing service that may reduce application-side model switching. Future writing must preserve the provider/model/version/data-policy boundary and the fact that routing changes which endpoint serves a request.

provider mapping / gateway / routing / cost / operability / governance / security

What do the current OpenRouter API and Auto Router documents establish about schema normalization, tool mapping, model restrictions, cost tiers, and provider selection?

[S1] SOURCE_CLASS: official_provider_docs | EXACT_TITLE: OpenRouter API Reference | AUTHOR_ORG: OpenRouter | CANONICAL_URL: https://openrouter.ai/docs/api_reference/overview | PUBLICATION_UPDATE_ACCESS: current API reference accessed 2026-09-14 00:16 JST | VERSION_RELEASE_TAG: current docs; API path /api/v1/chat/completions; no immutable docs release pin exposed | SUPPORTING_LOCATOR: lines 19-36 for API normalization/OpenAPI publication; lines 47-81 for request schema, tools, provider transformation, and tool_choice; lines 98-104 for OpenRouter-only models/route/provider/user fields | EVIDENCE_LABEL: VERIFIED_SPEC + PRODUCT_VOLATILE | RELATION: support for documented API boundary; limit for provider behavior. [S2] SOURCE_CLASS: official_provider_docs | EXACT_TITLE: Auto Router - Intelligent Model Selection | AUTHOR_ORG: OpenRouter | CANONICAL_URL: https://openrouter.ai/docs/guides/routing/routers/auto-router | PUBLICATION_UPDATE_ACCESS: current guide accessed 2026-09-14 00:16 JST | VERSION_RELEASE_TAG: current Auto Router docs; exact API/model/plugin semantics require recheck | SUPPORTING_LOCATOR: lines 450-476 for pattern allow/exclude restrictions and no-eligible-model failure; lines 481-487 for cost tiers and ranking; related links lines 610-613 for model fallback/provider selection | EVIDENCE_LABEL: VERIFIED_SPEC + PRODUCT_VOLATILE | RELATION: support for routing controls; limit for quality/availability. [S3] SOURCE_CLASS: official_provider_docs | EXACT_TITLE: OpenRouter | AUTHOR_ORG: OpenRouter | CANONICAL_URL: https://openrouter.ai/ | PUBLICATION_UPDATE_ACCESS: current product page accessed 2026-09-14 00:16 JST | VERSION_RELEASE_TAG: product page current; displayed model/provider counts and claims are volatile | SUPPORTING_LOCATOR: product page model/provider access, fallback, data-policy, and credit/API-key claims | EVIDENCE_LABEL: PRODUCT_VOLATILE | RELATION: context only; not independent benchmark or contract proof.

• ESTABLISHED [S1 support]: OpenRouter documents request/response schemas as similar to the OpenAI Chat API and says it normalizes the schema across models/providers. It publishes an OpenAPI description of its API.
• ESTABLISHED [S1 support]: For tool calling, the documentation states that tools may be passed through for providers implementing OpenAI's interface, transformed/mapped for custom interfaces, or transformed into a YAML template otherwise. This is an explicit provider-path distinction, not universal equivalence.
• ESTABLISHED [S2 support]: Auto Router documents allowed/excluded model patterns and a failure when restrictions leave no eligible model. It documents cost tiers from low through max and says a tier is a band, not a hard numeric ceiling; within a tier, models are ranked by market spend share.
• INFERENCE [S1+S2]: OpenRouter can be treated as a routing/control boundary, but route selection can change provider, model behavior, latency, cost, policy, and tool semantics. A normalized request is not evidence of normalized outcome quality.

Current docs are mutable and product-page counts are not a reproducible benchmark. Provider transformation may lose or alter parameters; tool YAML fallback changes the runtime contract. Cost tiers do not establish a fixed price, quality floor, data residency, or SLO. Model/provider availability, credits, API keys, data policy, and fallback behavior are account/plan/request dependent. No request was executed.

OpenRouter API revision/path; model ID and provider endpoint; allowed/excluded models; Auto Router plugin/version; provider preference and fallback; tool/structured-output support; API key/credits; provider data policy/ZDR/retention; region; rate/context limits; cost tier/max price; audit/logging; error/retry behavior; organization policy.

Evidence-only desk research. No OpenRouter key, credit purchase, model request, tool call, or provider route was used.

No model-selection, tool-transformation, cost, latency, fallback, data-policy, or cross-provider output-equivalence benchmark was run.

Provider route and request transformation must be recorded per call; prompts/results may traverse different provider boundaries. Audit needs requested model, selected provider/model, all fallback attempts, policy filters, data policy, token/cost, and result. Treat provider routing as an operational change, not a transparent implementation detail. Cost tiers/credits require reconciliation to provider invoices; not measured.

「OpenRouterは、複数model/providerへのAPIアクセスを一つのrequest形状へ寄せ、tool callingではproviderの実装に応じて透過・変換・YAML化を行うと文書化している。Auto Routerのallow／exclude／cost tier等はroute制御であり、モデル品質・価格上限・データ境界・SLOの保証ではない。」

Future update Work should pin API docs and model/provider catalog snapshots, then compare one direct-provider request with the same OpenRouter request using safe read-only prompts and no external tool side effect. Record schema transformation, route, fallback, cost, latency, data policy, and output/tool differences.

current provider/model catalog; route algorithm and ranking data; transformation edge cases; tool/schema semantics; provider-specific retention/region; max-price enforcement; fallback retry duplication; observability/audit; enterprise contract and SLO; independent benchmarks.

Do not cite OpenRouter's normalized schema as proof of provider equivalence. Do not convert a displayed model count, fallback feature, or Auto Router cost tier into a performance, quality, price, privacy, or availability guarantee. UNIT_CLOSE_STATUS: INDIVIDUAL_BOUNDED_CLOSE / EVIDENCE_RECORDED / UNKNOWN_PRESERVED

---