# AX Check: sim.ai
Checked 2026-10-16.

Agents can install, call the API, and price sim.ai fast
21 of 23 checklist items passed: quickstart, CLI install, API/MCP docs and all four pricing tiers are readable without login or guesswork.

## Onboarding needs a login

## Coding sessions
All three independent sessions completed the task. Two were reviewed on pricing and both correctly quoted Free $0, Pro $25, Max $100 per user/month, and custom Enterprise pricing straight from the pricing page, including credit limits and the annual discount.

### DeepSeek V4.1 Flash
[View public run](https://agents.withgauge.com/p/runs/ef8c7701-7881-4346-a317-a49f45e824ba) · [Read transcript](https://www.ax-check.com/sim.ai/sessions/deepseek.json)
Quoted Free $0 / Pro $25 / Max $100 per user/month / Enterprise custom from fetched pricing page, with credit allowances, per-seat billing, ~15% annual discount, and plan limits as basis. (seq 33, seq 39, seq 71)
#### End-to-end onboarding
- **Onboarding needs a login**: The agent researched the Sim API thoroughly (docs, SDK README, pricing) and built two working example scripts (raw fetch and SDK-based), but never obtained a Sim API key or workflow ID. No signup, login, or key-creation flow was attempted or available in the sandbox. The only live execution attempt was checking the script's own fail-fast behavior with environment variables unset, which just prints an error and exits 2 locally -- it never reached the hosted Sim API with real credentials. The agent explicitly reported this as the session's blocker.
  Event 71:

  ```text
  I could not make a live call because no `SIM_API_KEY` / `WORKFLOW_ID` is available in this environment. I built and validated the example (syntax + fail-fast path), but did not execute against Sim.
  ```
  Event 69:

  ```text
  Set SIM_API_KEY and WORKFLOW_ID first.
    API key:     Sim -> Account settings -> Sim API keys
    Workflow ID: the {workflowId} in .../workspace/{ws}/w/{workflowId}
  exit=2
  ```
  Event 46:

  ```text
  Create an API key Open Account settings → Sim API keys for a personal key, or Workspace settings → Sim API keys for a workspace key. Set SIM_API_KEY in your server environment.
  ```

#### Hallucinated URLs
None identified in this transcript.

#### Blockers
- **No Sim API key or workflow ID available to execute live**: Sim requires a human to create an API key via the dashboard (Account settings -> Sim API keys) and to build/deploy a workflow in the visual builder before any workflow ID exists to call. This is a normal authentication/setup requirement, not a product defect -- there is no self-service way for an unattended agent to mint credentials or a deployed workflow from the CLI/API alone. As a result the agent could only validate the example's syntax and local fail-fast path, never a real authenticated call.
  Event 71:

  ```text
  I could not make a live call because no `SIM_API_KEY` / `WORKFLOW_ID` is available in this environment. I built and validated the example (syntax + fail-fast path), but did not execute against Sim.
  ```
  Event 46:

  ```text
  Create an API key Open Account settings → Sim API keys for a personal key, or Workspace settings → Sim API keys for a workspace key.
  ```
  Event 46:

  ```text
  Deploy the workflow Open Deploy in the workflow builder and deploy the version you want to run. Deployment requires workspace Admin access and the applicable deployment permission.
  ```
- **Package name guesswork before finding the right SDK**: The agent's first guess at the SDK package name (simstudio-ai) returned a 404 from the npm registry; it recovered immediately by searching npm and finding the correct package (simstudio-ts-sdk). This was quickly self-corrected agent trial-and-error, not a lasting obstacle.
  Event 6:

  ```text
  npm error code E404
  npm error 404 Not Found - GET https://registry.npmjs.org/simstudio-ai - Not found
  ```

#### Suggested Changes
- **Add a CLI-based API-key and workflow bootstrap path to the quickstart**: The getting-started docs (docs.sim.ai/api-reference/getting-started) require creating an API key through the web dashboard and deploying a workflow through the visual builder before any API call can be made, which blocks fully unattended/scripted onboarding. Consider documenting (or adding) a CLI command, similar to the existing 'sim login' browser sign-in, that can also mint an API key and scaffold/deploy a minimal workflow non-interactively, then verify by having a fresh environment run the quickstart curl example end-to-end without touching the web UI.
  Event 46:

  ```text
  Create an API key Open Account settings → Sim API keys for a personal key, or Workspace settings → Sim API keys for a workspace key.
  ```
  Event 46:

  ```text
  The CLI also supports browser sign-in with sim login .
  ```

### Kimi K3
[View public run](https://agents.withgauge.com/p/runs/4e13f6ea-eb58-4e22-9045-b4c9d985a0cb) · [Read transcript](https://www.ax-check.com/sim.ai/sessions/kimi.json)
Quoted Free $0, Pro $25 and Max $100 per user/mo, Enterprise custom, from the pricing page. Named monthly billing, the 15% annual discount and credit limits; said Free covers the example. (seq 17, seq 99, README.md)
#### End-to-end onboarding
- **Onboarding needs a login**: The agent researched Sim's docs thoroughly and scaffolded a correct hosted-API example (SDK install, REST calls), but never obtained a real Sim API key. It only tested the code path with a self-invented dummy key (sk-sim-invalid-demo), which correctly returned 401 UNAUTHORIZED from the live API — this proves the request plumbing works, not that authenticated access was achieved. The agent explicitly flagged that key creation requires browser/account signup it cannot do itself.
  Event 90:

  ```text
  SIM_API_KEY=sk-sim-invalid-demo node list-workflows.mjs
  ```
  Event 92:

  ```text
  HTTP 401: { error: { code: 'UNAUTHORIZED', message: 'Invalid API key' } }
  ```
  Event 99:

  ```text
  One manual step I can't do from this sandbox: **API key creation requires a sim.ai account, and signup/login is browser/OAuth-based.**
  ```

#### Hallucinated URLs
None identified in this transcript.

#### Blockers
- **No self-service way to obtain a Sim API key**: Sim requires creating an account and generating an API key through the hosted web app (Account settings → Sim API keys), which needs browser/OAuth login. This is a normal product authentication requirement, not a defect — the agent correctly identified it as a stopping point rather than inventing credentials.
  Event 99:

  ```text
  API key creation requires a sim.ai account, and signup/login is browser/OAuth-based.
  ```
- **npm package name guesses failed before finding correct package**: The agent tried three plausible but incorrect npm package names (@simstudio/sdk, simstudio-sdk, sim-sdk) before discovering the actual package is simstudio-ts-sdk via the docs' llms.txt. This was quickly self-corrected using documentation rather than guesswork, so it's a minor friction point, not a lasting blocker.
  Event 32:

  ```text
  npm error 404 Not Found - GET https://registry.npmjs.org/@simstudio%2fsdk - Not found
  ```
  Event 47:

  ```text
  SDKs: `simstudio-ts-sdk` (npm) and `simstudio-sdk` (PyPI).
  ```

#### Suggested Changes
- **Publish the SDK package name prominently near the top of the quickstart**: The agent guessed three wrong npm package names (@simstudio/sdk, simstudio-sdk, sim-sdk) before finding the correct simstudio-ts-sdk, only surfaced deep in llms.txt. Add the exact install command (e.g. 'npm install simstudio-ts-sdk') to the top of /api-reference/getting-started or /getting-started so it's the first thing a developer sees; verify by searching the page for the literal package name before any code sample.
  Event 32:

  ```text
  npm error 404 Not Found - GET https://registry.npmjs.org/@simstudio%2fsdk - Not found
  ```
  Event 47:

  ```text
  SDKs: `simstudio-ts-sdk` (npm) and `simstudio-sdk` (PyPI).
  ```
- **Fix the broken /sdks/typescript documentation link**: A direct fetch to https://docs.sim.ai/sdks/typescript returned 404, forcing a roundabout path through llms.txt to find the working /api-reference/typescript page. Check internal links/redirects referencing the old /sdks/typescript path and point them to /api-reference/typescript; verify by curling the URL and confirming a 200 or proper redirect.
  Event 23:

  ```text
  https://docs.sim.ai/sdks/typescript
  ```
  Event 25:

  ```text
  308
  404
  
  ```

### Qwen 3.8 Max
[View public run](https://agents.withgauge.com/p/runs/77621916-1ac7-4e12-af1a-df7ab9d29aea) · [Read transcript](https://www.ax-check.com/sim.ai/sessions/qwen.json)

#### End-to-end onboarding
- **Onboarding needs a login**: The agent never obtained real Sim credentials. It searched the environment for an existing SIM_API_KEY and found none, confirmed there is no self-service/headless account-or-key creation API, and explicitly stated credential bootstrap requires the web UI (Account/Workspace settings) which it cannot do headlessly. It only tested the hosted API with a deliberately bogus key, which correctly returned 401 Unauthorized — this proves the API wiring works but is not an authenticated operation. No workflow was created, deployed, or executed with a valid credential.
  Event 11:

  ```text
  env | grep -i -E "sim|api|key|token" | sed 's/=.*/=<redacted>/' | head -30
  ```
  Event 93:

  ```text
  error: UNAUTHORIZED (HTTP 401): Invalid API key
  exit=1
  ```
  Event 161:

  ```text
  Only one thing: **no Sim credentials in this environment** (no `SIM_API_KEY`, no CLI profile), and creating one requires web signup — I can't do that headlessly.
  ```

#### Hallucinated URLs
None identified in this transcript.

#### Blockers
- **No self-service way to obtain a Sim API key**: Product behavior/session limitation, not an agent error: Sim requires creating API keys through the web UI (Account settings or Workspace settings) or via sim login, which needs a browser for OAuth or interactive pairing. There is no headless account/key creation endpoint, so the agent could not provision real credentials and had to stop short of an authenticated run.
  Event 58:

  ```text
  Open Account settings → Sim API keys to create a personal key, or Workspace settings → Sim API keys to create a workspace key.
  ```
  Event 161:

  ```text
  no Sim credentials in this environment (no `SIM_API_KEY`, no CLI profile), and creating one requires web signup — I can't do that headlessly
  ```

#### Suggested Changes
- **Fix broken docs links under /platform/credits-billing-limits and /workflows/api-deployment**: Guessed documentation paths based on nav naming conventions (e.g. 'platform/credits-billing-limits', 'administration/credits-billing-limits', 'workflows/api-deployment') returned the docs site's 404 page. The real page was eventually found at /platform/costs. Product owner should check docs.sim.ai redirects/sitemap so common guessable paths for billing and API-deployment topics resolve or 301 to the correct page (/platform/costs, /workflows/deployment/api).
  Event 40:

  ```text
  == platform/credits-billing-limits
   Page Not Found | Sim Docs
  ```
  Event 40:

  ```text
  == workflows/api-deployment
   Page Not Found | Sim Docs
  ```
- **Add a documented path to an API key without web-UI signup**: The getting-started and authentication docs (docs.sim.ai/api-reference/getting-started, /api-reference/authentication) state keys are only created via Account settings → Sim API keys or Workspace settings → Sim API keys in the web UI, with sim login needing a browser. For headless/CI and agentic developer workflows, document a non-interactive key-issuance path (if one exists) in the Authentication page so automated setups do not require a human to click through the dashboard.
  Event 58:

  ```text
  Open Account settings → Sim API keys to create a personal key, or Workspace settings → Sim API keys to create a workspace key.
  ```

### Task given to each agent
Help me build a simple example using Sim. Tell me how pricing works, and briefly tell me whether this product will be easy for you to manage. Let me know if you get blocked. If this product has no developer workflow you can act on, say so plainly and stop. Stay light: use the hosted product through its SDK or API. Do not start local service stacks or wait for long-running commands; if the quickstart requires either, say so plainly and stop.

No product credentials were supplied and no purchases were authorized.

## Score: B · 84/100 (provisional)
Grades come from completed site checks. Coding sessions and skipped checks do not affect the score.

### Clarity
- **Failed** — Homepage answers Markdown requests

  ```text
  Homepage returned text/html for a text/markdown request; no Markdown representation offered.
  ```

- **Pass** — llms.txt provides an actionable documentation index

  ```text
  llms.txt links docs index, full text, API reference, CLI, MCP, and SDK pages.
  ```

- **Pass** — llms.txt provides navigation guidance

  ```text
  llms.txt groups links under Platform, Solutions, Docs, Integrations, and Optional headings.
  ```

- **Pass** — llms.txt mentions offered API, MCP, and skills

  ```text
  llms.txt links API reference, MCP docs, and CLI skills pages.
  ```

- **Pass** — A compact guide representation exists

  ```text
  llms.txt is a compact Markdown index of Sim's platform, docs, integrations, and models.
  ```

- **Pass** — A focused guide is directly retrievable

  ```text
  docs.sim.ai/api-reference/getting-started.md serves a focused Markdown quickstart with curl, TS, Python.
  ```

- **Pass** — Equivalent instructions fit a token budget

  ```text
  The .md quickstart is 2650 tokens, well under the 8000-token budget.
  ```

- **Skipped** — Product-docs links survive format changes

  ```text
  Homepage Markdown is unsupported, so link preservation across formats cannot be measured.
  ```

- **Pass** — The compact guide is independently actionable

  ```text
  API getting-started gives concrete first call: create key, find workflow ID, deploy, curl/TS/Python execute.
  ```

- **Pass** — Install and next-step links resolve

  ```text
  Sampled install/next-step links (docs, CLI, API, MCP, SDK pages) fetched successfully.
  ```


### Onboarding
- **Pass** — Docs lead to a relevant quickstart

  ```text
  API getting-started guide gives concrete first steps: create key, find workflow ID, deploy, call.
  ```

- **Pass** — Installation commands are extractable

  ```text
  CLI install commands shown: 'bun add -g sim', 'bunx sim --help', npm/pnpm supported.
  ```

- **Pass** — Code examples are available without interaction

  ```text
  curl, TypeScript and Python examples shown inline without interaction.
  ```

- **Pass** — Prerequisites and auth boundaries are explicit

  ```text
  Auth page states X-API-Key requirement and where to create keys.
  ```


### Pricing
- **Pass** — Pricing is readable without interaction

  ```text
  Sim's pricing page renders all four plan cards with prices and limits in plain HTML.
  ```

- **Pass** — Prices are stated, not gated

  ```text
  Prices stated: Free $0, Pro $25, Max $100 per user/month; Enterprise custom.
  ```

- **Pass** — Pricing units and limits are explicit

  ```text
  Pricing page lists credits, concurrency, rate limits, storage, tables and retention per plan.
  ```

- **Pass** — Agents identify pricing and its assumptions

  ```text
  2 of 3 sessions were judged on pricing; 0 fell short. DeepSeek V4.1 Flash: Quoted Free $0 / Pro $25 / Max $100 per user/month / Enterprise custom from fetched pricing page, with credit allowances, per-seat billing, ~15% annual discount, and plan limits as basis. (seq 33, seq 39, seq 71) Kimi K3: Quoted Free $0, Pro $25 and Max $100 per user/mo, Enterprise custom, from the pricing page. Named monthly billing, the 15% annual discount and credit limits; said Free covers the example. (seq 17, seq 99, README.md) This behavioural item does not affect the fast grade.
  ```


### Activation
- **Pass** — An API reference or OpenAPI spec is reachable

  ```text
  API getting-started page links a downloadable OpenAPI 3.1 spec, and the spec itself returns HTTP 200.
  ```

- **Pass** — An MCP server is documented and well-formed

  ```text
  MCP docs cover registering remote Streamable HTTP servers, auth headers, OAuth, and tool access policies.
  ```

- **Pass** — A CLI install path is documented

  ```text
  CLI page documents global install via bun add -g sim plus bunx sim, npm and pnpm.
  ```

- **Pass** — SDK packages resolve on their registries

  ```text
  npm registry lookup for the sim CLI package returned HTTP 200; Python and TypeScript SDKs are documented.
  ```

- **Pass** — Agent skills are published

  ```text
  Skills are published: CLI skills commands and API reference endpoints create, list, and manage skills.
  ```



[Full report data](https://www.ax-check.com/sim.ai/report.json)