# Migrate from the old API > Every change from the old tool API, with each old call next to its new one, and a prompt that moves your code for you. Source: https://docs.fous.com/guides/migration Index: https://docs.fous.com/llms.txt Your API keys, the base URL and the MCP server stay the same. Tools are now methods: each operation of a tool is one method, named by its site's domain and the operation, such as `companiesmarketcap.com/get_company_size`. Private tools stay private to your organization. `POST /v1/query`, `GET /v1/query/requests/{request_id}` and `POST /v1/query/cancel` keep working [until 10 November 2026](#until-the-sunset). Every other old endpoint has stopped. ## Run a method ```diff - POST /v1/query - Idempotency-Key: 6a1f0c2e + POST /v1/runs { - "api": "@companiesmarketcap", - "operation": "get_company_size", + "method": "companiesmarketcap.com/get_company_size", "input": { "company": "Coca-Cola" } } ``` ```diff { - "success": true, - "data": { - "output": { "ticker": "KO", "market_cap_usd": 404720000000 }, - "receipt": { - "request_id": "req_run_01m69eaghdfsdrysprnyfwr8xy", - "billing": { "charged_credits": 1 } - } - } + "id": "run_01m69eaghdfsdrysprnyfwr8xy", + "status": "completed", + "data": { "ticker": "KO", "market_cap_usd": 404720000000 }, + "cost": { "credits": 1 }, + "duration_ms": 1693 } ``` - `"version": 2` is now `"method": "companiesmarketcap.com/get_company_size@2"`. - `visibility`, `stream`, `response` and the `Idempotency-Key` header are gone. Your own method is found before a public one with the same slug; take the fields you need from `data`. - To find a slug, `GET /v1/search?platform=companiesmarketcap.com` lists the site's methods, and every old-format answer names its method in `data.receipt.method`. ## Slow runs The old call waited up to 170 seconds. `POST /v1/runs` waits `wait` seconds (0 to 60, 30 by default), then answers `202` with `"status": "running"` and the run's `id`: ```diff - GET /v1/query/requests/req_run_01m69eaghdfsdrysprnyfwr8xy + GET /v1/runs/run_01m69eaghdfsdrysprnyfwr8xy?wait=30 - POST /v1/query/cancel {"idempotency_key": "6a1f0c2e"} + POST /v1/runs/run_01m69eaghdfsdrysprnyfwr8xy/cancel ``` ## Errors ```diff { - "success": false, "error": { - "type": "authentication_error", - "code": "revoked_api_key", - "status": 401, - "retryable": false, + "code": "unauthorized", + "reason": "revoked_api_key", "message": "API key has been revoked.", + "next_step": "Send Authorization: Bearer . Create a key in Fous Studio: …" } } ``` Branch on the HTTP status and `error.code`. The codes that changed: ```text invalid_api_key, expired_api_key, revoked_api_key → unauthorized (401) insufficient_balance → insufficient_credits (402) spend_limit_exceeded, monthly_spend_limit_exceeded → insufficient_credits (402) rate_limit_exceeded, organization_rate_limit, organization_concurrency_limit → rate_limited (429) unknown_api_slug, unknown_operation → not_found (404) auth_required, credentials_missing → connection_required source_blocked → upstream_blocked (503) source_rate_limited, upstream_http_error → upstream_error (503) execution_timeout → upstream_timeout (503) internal_error → server_error (500) invalid_input (400) → invalid_input (422) ``` Where the old code was more specific, `error.reason` keeps it, such as `revoked_api_key`, `spend_limit` or `site_rate_limited`. Every code is in [Errors and limits](https://docs.fous.com/guides/errors.md). ## Find methods ```diff - GET /v1/catalog?query=coca-cola+market+cap + GET /v1/search?query=coca-cola+market+cap - GET /v1/catalog/suggest?query=coca + GET /v1/search?query=coca&suggest=true - GET /v1/catalog/detail?api=@companiesmarketcap + GET /v1/search?platform=companiesmarketcap.com + GET /v1/methods/companiesmarketcap.com/get_company_size ``` The old `data.items`, each a tool with its `operations`, is now `results`, one method each, with its `slug`, `effect` and `input_schema`. `/v1/catalog/categories`, `/v1/catalog/sitemap` and `/v1/catalog/tools` are gone. ## Your methods ```diff - GET /v1/tools + GET /v1/methods - GET /v1/tools/@example + GET /v1/methods/example.com/list_invoices - DELETE /v1/tools/@example/methods/{method_id} + DELETE /v1/methods/example.com/list_invoices - PUT /v1/catalog/version-preference {"operation_id": 1820} + PATCH /v1/methods/companiesmarketcap.com/get_company_size {"pinned_version": 2} ``` `DELETE /v1/tools/{api}` deleted every operation of a tool; delete each method now. `/restore` and `/environment` are gone. ## Builds ```diff POST /v1/builds { - "prompt": "List my invoices on example.com", - "url": "https://example.com/billing", + "query": "List my invoices on example.com", + "platform": "example.com", "visibility": "private", - "connections": { "billing": "conn_01m5kvvt1pkybmt03dyvhyd5m2" }, - "environment": { "EXAMPLE_API_KEY": "sk_live_…" } + "connections": ["conn_01m5kvvt1pkybmt03dyvhyd5m2"] } ``` - `visibility` is **required** for a new method: `"public"` (anyone can find and run it) or `"private"` (your organization only). The old default was private. - `api` or `method_id`, to change a method, is now `method`. A key in `environment` becomes an `api_key` connection ([below](#connections)). `contribute` and `risk_acknowledgment` are gone. - `/approvals/{approval_id}` is gone: a build that writes does its action once, for real, with the `input` you send. `/retry` is gone: send `POST /v1/builds/{id}/messages` with `{"text": "…"}`, or start a new build. ## Connections ```diff - POST /v1/connections/attempts {"website_url": "https://example.com"} + POST /v1/connections {"platform": "example.com", "type": "session", "attest": true} - GET /v1/connections/attempts/{attempt_id} + GET /v1/connections/{id} - POST /v1/connections/attempts/{attempt_id}/submit {"step_id": "…", "fields": {…}} + POST /v1/connections/{id}/sign-in {"step_id": "…", "fields": {…}} - POST /v1/connections/attempts/{attempt_id}/retry + POST /v1/connections/{id}/sign-in {"attest": true, "restart": true} - POST /v1/connections/attempts/{attempt_id}/cancel + DELETE /v1/connections/{id}/sign-in ``` A saved key is a connection too: ```diff - PUT /v1/variables - {"site": "example.com", "name": "API_KEY", "value": "sk_live_…"} + POST /v1/connections + {"platform": "example.com", "type": "api_key", "api_key": "sk_live_…", "attest": true} ``` `consent` is now `"attest": true`. `challenge_id` and `/confirm` are gone: a connection turns active when its sign-in ends. `GET /v1/connections` lists sign-ins and keys alike. ## Account ```diff - GET /v1/auth - GET /v1/usage + GET /v1/account ``` `/v1/account` has the organization, credits, plan limits and the key; spending history is in Studio. Rating a call (`/feedback`) is gone. ## MCP tools The server address is the same, and clients load the new tools when they reconnect. Update prompts or code that name the old ones: ```text fous_search_tools → search fous_run_tool → run fous_run_action → run_action fous_get_run, fous_get_build → get_run fous_get_tool, fous_delete_tool → methods fous_build_tool → build fous_connect_account, fous_variables → connect fous_connections → connections fous_status → account ``` New: `query` (describe what you want; Fous picks the methods and runs them), `stop` and `builds`. ## Until the sunset The three old `/v1/query` endpoints answer in the old shape, run on the new system and cost the same 1 credit. Each answer carries `Deprecation`, `Sunset` (when they stop) and `Link` (this guide). Until then: - `request_id` is the run's id with `req_` in front. - `data.receipt.method` is the method to send `POST /v1/runs`. - `response.format` `text` or `markdown`, `response.schema` and `response.mapping` answer `400`; `include` and `exclude` still work. - A stream sends the `accepted` stage, then the result. From 10 November 2026, 00:00 UTC (the `Sunset` date), they answer `410`. Questions: [hello@fous.com](mailto:hello@fous.com).