> ## Documentation Index > Fetch the complete documentation index at: https://docs.gumloop.com/llms.txt > Use this file to discover all available pages before exploring further. # Route a message to a model > Ask Gumloop Chew — the model router behind **Auto** — which model it would use for a given message, and why. Chew is a router, not a model: `router` is always `gumloop-chew`, and the concrete model it selected is `route.model`. This endpoint returns a decision only. It does not run the selected model or its fallbacks. The routing judgement consumes credits and is bounded by the caller's model access. Omit `models` to use the deduplicated union of Chew's lane chains, not every model the caller may use. Restricted candidates can appear with `status: "restricted"`; they are never selected or included in `fallback_models`. Team scope requires actual team membership, even within the same organization. Personal API keys and OAuth are supported; this is not team-key-only. ## OpenAPI ````yaml post /models/route openapi: 3.0.0 info: title: Public API version: 1.0.0 servers: - url: https://api.gumloop.com/api/v1 security: [] paths: /models/route: post: tags: - Models summary: Route a message to a model description: > Ask Gumloop Chew — the model router behind **Auto** — which model it would use for a given message, and why. Chew is a router, not a model: `router` is always `gumloop-chew`, and the concrete model it selected is `route.model`. This endpoint returns a decision only. It does not run the selected model or its fallbacks. The routing judgement consumes credits and is bounded by the caller's model access. Omit `models` to use the deduplicated union of Chew's lane chains, not every model the caller may use. Restricted candidates can appear with `status: "restricted"`; they are never selected or included in `fallback_models`. Team scope requires actual team membership, even within the same organization. Personal API keys and OAuth are supported; this is not team-key-only. operationId: routeModel requestBody: required: true content: application/json: schema: type: object additionalProperties: false properties: input: description: >- The message to route. `message` is accepted as an alias. A string or an array of `{type: text, text: ...}` parts. oneOf: - type: string - type: array items: type: object models: type: array maxItems: 50 minItems: 1 uniqueItems: true description: >- Candidate model IDs to choose between. IDs must be nonempty, unique after remapping, and registered. Omit to use Chew's lane-chain union. items: type: string history: type: array maxItems: 20 description: Prior turns, oldest first, for context. items: type: object additionalProperties: false required: - role - content properties: role: type: string enum: - user - assistant content: description: >- Message text, as a string or text parts. `input` and `message` are accepted as aliases. oneOf: - type: string - type: array items: type: object model: type: string maxLength: 200 description: >- The model that produced this turn. Assistant messages only. agent: type: object additionalProperties: false description: >- Optional context about the agent the message is for. Sharper context produces a sharper route. properties: name: type: string maxLength: 200 description: type: string maxLength: 2000 system_prompt: type: string maxLength: 20000 team_id: type: string description: >- Scope model availability and credit attribution to a team the caller belongs to. required: - input responses: '200': description: The routing decision. content: application/json: schema: type: object properties: router: type: string description: Always `gumloop-chew`. route: type: object properties: model: type: string description: The model Chew selected. lane: type: string description: >- The capability lane of the selected model (`micro`, `light`, `standard`, `plus`, or `max`). verdict_lane: type: string description: >- The lane the message was judged to need, before any adjustment. adjustment: type: string nullable: true description: '`escalated`, `downgraded`, or null.' reasoning_effort: type: string nullable: true fallback_models: type: array description: >- Eligible models to try, in order, if the selected one is unavailable. Restricted candidates are excluded. items: type: string fail_closed: type: boolean description: >- True when routing could not complete and a safe default was used. candidates: type: array description: >- Every candidate considered. Restricted candidates are reported, not selected. items: type: object properties: requested_model: type: string model: type: string lane: type: string basis: type: string description: >- How the lane was assigned (`catalog`, `price`, or `rating`). status: type: string description: '`eligible` or `restricted`.' examples: route: summary: Illustrative routing decision value: router: gumloop-chew route: model: gpt-5.6-luna lane: light verdict_lane: light adjustment: null fallback_models: - claude-opus-5 fail_closed: false candidates: - requested_model: claude-opus-5 model: claude-opus-5 lane: plus basis: catalog status: eligible - requested_model: gpt-5.6-luna model: gpt-5.6-luna lane: light basis: catalog status: eligible '400': description: >- Invalid request body, unknown model IDs, duplicate IDs after remapping, or extra properties. '401': description: Unauthorized — missing or invalid API key. '402': description: Credit limit exceeded. '403': description: >- Forbidden — Chew is restricted, no supplied candidate is permitted, or the caller is not a member of the requested team. '404': description: User profile not found. security: - bearerAuth: [] x-codeSamples: - lang: bash label: cURL source: | curl -X POST 'https://api.gumloop.com/api/v1/models/route' \ -H 'Authorization: Bearer YOUR_ACCESS_TOKEN' \ -H 'Content-Type: application/json' \ -d '{ "input": "Summarize this email thread", "models": ["claude-opus-5", "gpt-5.6-luna"] }' components: securitySchemes: bearerAuth: type: http scheme: bearer description: >- A personal API key or an [OAuth 2.0](/api-reference/oauth) access token. Personal API keys also require the `x-auth-key` header with your user ID. ````