# AX Check: sinch.com Checked 2026-09-29. Sinch pricing and quickstart are clear, but llms.txt is missing SMS, Voice and RCS prices are stated openly with clear units. The homepage offers no Markdown version and llms.txt returns a 404, so agents must rely on regular docs pages. ## Onboarding needs a login ## Coding sessions Two of three independent sessions (DeepSeek V4.1 Flash, Kimi K3) completed the task and reported concrete per-message and per-minute pricing along with clear assumptions like destination country and carrier fees. The third session, Qwen 3.8 Max, did not complete. ### DeepSeek V4.1 Flash [View public run](https://agents.withgauge.com/p/runs/34a2fd01-6c9f-4251-9665-92bd7dac12f2) · [Read transcript](https://www.ax-check.com/sinch.com/sessions/deepseek.json) Final output gives concrete rates (~$0.0078/SMS, ~$0.02/MMS, ~$1-2/mo numbers) while naming assumptions: US destination, published rates, carrier fees additional, contract/volume variance, and a link to verify. #### End-to-end onboarding - **Onboarding needs a login**: The agent never obtained real Sinch credentials on its own. It confirmed reachability to Sinch's hosted SMS API and built a working example using the official @sinch/sdk-core SDK, but the only live-API call used deliberately fake dummy credentials, which correctly returned 401 Unauthorized. This proves the request path is correct but is not an authenticated operation. No account signup or key retrieval occurred; the agent stated the workspace has no Sinch account or API keys and it was blocked on credentials. Event 55: ```text [Sinch SDK][Debug] [BatchesApi][SendSMS][401] HTTP method: POST URL: https://us.sms.api.sinch.com/xms/v1/dummy_plan/batches ``` Event 74: ```text This workspace has no Sinch account or API keys, so I could not perform an actual send. ``` Event 54: ```text SINCH_SERVICE_PLAN_ID=dummy_plan SINCH_API_TOKEN=dummy_token SINCH_FROM=+12025550123 SINCH_TO=+12025550124 node send-sms.mjs ``` #### Hallucinated URLs None identified in this transcript. #### Blockers - **No Sinch account credentials available in the sandbox**: The environment had no Sinch API keys, project ID, or service plan ID. This is a missing-credentials limitation of the test environment/session, not a product defect since Sinch requires account signup and dashboard-issued keys as normal practice. The agent correctly identified this, built the example to accept env-var credentials, validated the request path with dummy values (which correctly returned 401), then stopped rather than faking success. Event 74: ```text This workspace has no Sinch account or API keys, so I could not perform an actual send. ``` Event 18: ```text sms.api.sinch.com -> 401 (76.223.66.78) ``` #### Suggested Changes None identified in this transcript. ### Kimi K3 [View public run](https://agents.withgauge.com/p/runs/21df4792-cd57-4529-a5a6-f1c9197b9ed2) · [Read transcript](https://www.ax-check.com/sinch.com/sessions/kimi.json) Final output gives per-segment/per-minute pay-as-you-go pricing with assumptions called out: US-destination rate, number rental ~$1-2/mo, trial credit, and flags rates vary by country and to check sinch.com/pricing for authoritative numbers. #### End-to-end onboarding - **Onboarding needs a login**: The agent never obtained real Sinch credentials. It installed the @sinch/sms SDK and sent one unauthenticated test POST that returned HTTP 401, which only confirms the endpoint exists, not that any authenticated operation occurred. The agent explicitly states account creation requires a human step it cannot complete, and stops there. Event 16: ```text curl -s -o /dev/null -w "%{http_code}" -X POST "https://us.sms.api.sinch.com/xms/v1/test_plan/batches" -H "Content-Type: application/json" -d '{"to":["+15551234567"],"body":"ping"}'; echo ``` Event 28: ```text ❌ **I am blocked at credentials.** Sending a real message requires a Sinch account (dashboard.sinch.com → SMS service plan → Service Plan ID + API Token, plus a rented number for US traffic). Signup is free with trial credit, but account creation is a human step I can't complete. ``` #### Hallucinated URLs None identified in this transcript. #### Blockers - **No self-service path to real Sinch credentials**: Sending an actual SMS requires a Service Plan ID and API Token obtained by signing up at dashboard.sinch.com, a human browser step the agent could not perform. This is a normal login/account-creation requirement, not a product defect, and the agent correctly stopped rather than faking success. Event 28: ```text Signup is free with trial credit, but account creation is a human step I can't complete. Drop in the three env vars in the README and the script runs as-is. ``` #### Suggested Changes None identified in this transcript. ### Qwen 3.8 Max [View public run](https://agents.withgauge.com/p/runs/e1ab4e83-9c2a-4e81-b17e-12263c17a475) · [Read transcript](https://www.ax-check.com/sinch.com/sessions/qwen.json) Session findings unavailable. ### Task given to each agent Help me build a simple example using Sinch. 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 · 65/100 (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 even when text/markdown was requested; no Markdown representation offered. ``` - **Failed** — llms.txt provides an actionable documentation index ```text https://sinch.com/llms.txt returned HTTP 404, so no documentation index exists. ``` - **Skipped** — llms.txt provides navigation guidance ```text No llms.txt body was returned (404), so navigation guidance cannot be judged. ``` - **Skipped** — llms.txt mentions offered API, MCP, and skills ```text No llms.txt body was returned (404), so API/MCP/skills mentions cannot be judged. ``` - **Pass** — A compact guide representation exists ```text Verification getting-started page served as text/markdown at .md URL, a standalone Markdown representation. ``` - **Pass** — A focused guide is directly retrievable ```text Getting-started guide directly retrievable as Markdown with account signup and language SDK steps. ``` - **Pass** — Equivalent instructions fit a token budget ```text Markdown guide is 201 tokens, well under the 8000-token budget. ``` - **Skipped** — Product-docs links survive format changes ```text Homepage Markdown unsupported, so link preservation across formats cannot be measured. ``` - **Pass** — The compact guide is independently actionable ```text Verification getting-started gives concrete steps: sign up, select language SDK, then build. ``` - **Pass** — Install and next-step links resolve ```text Getting-started and Skills pages fetched successfully; install and next-step links resolve. ``` ### Onboarding - **Pass** — Docs lead to a relevant quickstart ```text Verification API getting-started guide walks through setup with per-language SDK quickstarts. ``` - **Pass** — Installation commands are extractable ```text Getting-started links to SDK install pages and Sinch CLI installation guide. ``` - **Skipped** — Code examples are available without interaction ```text Fetched getting-started page links to per-language guides but shows no inline code examples. ``` - **Pass** — Prerequisites and auth boundaries are explicit ```text Guide states a free Sinch Build Dashboard account is required and links signup. ``` ### Pricing - **Pass** — Pricing is readable without interaction ```text SMS, Voice and RCS pricing pages render prices directly in HTML without interaction. ``` - **Pass** — Prices are stated, not gated ```text SMS page lists $0.0078/msg, Voice $0.01/min, RCS $0.0078/msg openly. ``` - **Pass** — Pricing units and limits are explicit ```text Units explicit: per outbound message, per minute, per month, setup one-time fee. ``` - **Pass** — Agents identify pricing and its assumptions ```text 2 of 3 sessions were judged on pricing; 0 fell short. DeepSeek V4.1 Flash: Final output gives concrete rates (~$0.0078/SMS, ~$0.02/MMS, ~$1-2/mo numbers) while naming assumptions: US destination, published rates, carrier fees additional, contract/volume variance, and a link to verify. Kimi K3: Final output gives per-segment/per-minute pay-as-you-go pricing with assumptions called out: US-destination rate, number rental ~$1-2/mo, trial credit, and flags rates vary by country and to check sinch.com/pricing for authoritative numbers. This behavioural item does not affect the fast grade. ``` ### Activation - **Pass** — An API reference or OpenAPI spec is reachable ```text Verification API reference pages offer downloadable OpenAPI verification.json and verification.yaml specs. ``` - **Skipped** — An MCP server is documented and well-formed ```text Docs mention MCP server connect options but no fetched page documents a well-formed MCP server. ``` - **Pass** — A CLI install path is documented ```text Functions & CLI page links Sinch CLI installation and CLI reference for the sinch CLI. ``` - **Skipped** — SDK packages resolve on their registries ```text SDK install links exist but no registry lookup result for a Sinch package was fetched. ``` - **Pass** — Agent skills are published ```text Sinch Skills page documents installable SKILL.md skills via npx skills add sinch/skills. ``` [Full report data](https://www.ax-check.com/sinch.com/report.json)