# AX Check: blocksize.info Checked 2026-10-27. Docs and MCP setup are solid, but pricing trips up agents. Prices are posted publicly (€49/€299/€799 tiers), yet 1 of 3 agent sessions failed to find a dollar figure and assumed it was sign-up gated. ## Onboarding needs a login ## Coding sessions All three sessions completed. Kimi K3 correctly quoted the €49/€299/€799 monthly and yearly tiers with trial terms straight from the pricing page. Qwen 3.8 Max searched thoroughly but concluded no public dollar prices exist. DeepSeek V4.1 Flash listed tier limits and the 14-day trial but gave no cost figure, assuming prices only appear at sign-up. ### DeepSeek V4.1 Flash [View public run](https://agents.withgauge.com/p/runs/30f5f10a-b321-4cc6-835d-b29fd9b43cf0) · [Read transcript](https://www.ax-check.com/blocksize.info/sessions/deepseek.json) Gave no cost figure for any paid plan. It listed tier limits and a free 14-day trial, then said dollar amounts only appear at sign-up, so no cost was stated with assumptions (seq 35, seq 69, seq 92, README.md) #### End-to-end onboarding - **Onboarding needs a login**: The agent researched the live Blocksize API extensively (docs, OpenRPC/OpenAPI specs, llms.txt) and built a working example script, but it explicitly refused to create an account or obtain an API key, since doing so would require sign-up/payment-details entry. All authenticated calls (WebSocket auth and HTTP JSON-RPC) were tested only with a fake/dummy key and returned 'invalid API key' / 'unauthenticated' errors. No real credentials were ever obtained or used, so no authenticated product operation was demonstrated. Event 92: ```text I couldn't complete an **authenticated** end-to-end call because no Blocksize API key exists in this environment, and I won't create an account or enter payment details. ``` Event 80: ```text error: {"code":4001,"message":"invalid API key","data":"token not found"} ``` Event 84: ```text http error: 4000: unauthenticated ``` #### Hallucinated URLs None identified in this transcript. #### Blockers - **No self-service API key without sign-up/payment details**: The product requires creating an account via the customer portal to obtain an API key. The agent deliberately avoided this step since the task restricted it from entering payment details or signing up, so it never obtained real credentials. This is a normal login/account-creation requirement, not a product defect, and it fully blocked authenticated verification of the example. Event 92: ```text I couldn't complete an **authenticated** end-to-end call because no Blocksize API key exists in this environment, and I won't create an account or enter payment details. ``` Event 36: ```text As a user of Blocksize, you can manage your subscription details by logging into the customer portal ``` #### Suggested Changes - **Publish concrete dollar pricing on the docs/pricing pages**: The agent scraped api-docs.json, the pricing page, and the main JS bundle but found only plan names, rate limits, and a trial note — no dollar figures. Add explicit per-plan pricing (e.g., USD/month) to https://blocksize.dev/pricing or the api-docs.json 'Rate Limits' section so agents and developers don't have to infer pricing is sign-up-only. Event 58: ```text === dollar amounts === 21 $1 9 $2 8 $3 ``` Event 36: ```text ### Developer\n- Included access: Real-Time VWAP, Real-Time Bid/Ask, 24-Hour VWAP, 30-Minute VWAP\n- Active feeds: 5\n- API keys: 1 ``` ### Kimi K3 [View public run](https://agents.withgauge.com/p/runs/b82e9322-a7a1-455b-8106-021eb5cc0000) · [Read transcript](https://www.ax-check.com/blocksize.info/sessions/kimi.json) Quoted €49/€299/€799 monthly and yearly prices tied to tier, active-feed/seat/history limits, 15% yearly saving and 14-day no-card trial, sourced from pricing page (seq 43, seq 109, README.md) Session findings unavailable. ### Qwen 3.8 Max [View public run](https://agents.withgauge.com/p/runs/4c21265e-9c6f-4d74-9bb7-929db6af7d0d) · [Read transcript](https://www.ax-check.com/blocksize.info/sessions/qwen.json) Explained subscription tiers with documented limits and a 14-day free trial; said no public dollar prices exist after searching the site and bundle, and quoted no unsupported number (seq 41, seq 49, seq 59, seq 94) #### End-to-end onboarding - **Onboarding needs a login**: The agent discovered Blocksize is a real hosted crypto market-data API with machine-readable docs (llms.txt, api-docs.json) and built a working WebSocket JSON-RPC example. It never obtained an API key itself: account/API-key creation requires a browser-based signup flow that the agent explicitly could not complete. It tested the script with a dummy key and only reached the documented 'invalid API key' error — no authenticated operation against real data was ever demonstrated. Event 94: ```text running the example against live data requires an API key, and signup (`https://matrix.blocksize.capital/auth/open/sign-up`) is a browser flow I can't complete for you ``` Event 83: ```text RuntimeError: authentication_logon failed: {'code': 4001, 'message': 'invalid API key', 'data': 'token not found'} ``` Event 92: ```text Set BLOCKSIZE_API_KEY (create one at https://matrix.blocksize.capital/auth/open/sign-up, 14-day free trial). nokey_exit=1 ``` #### Hallucinated URLs None identified in this transcript. #### Blockers - **API key signup requires browser-based human action**: The product requires creating an account and API key through a browser sign-up flow at the customer portal. This is normal product authentication (not a defect), but it blocked the agent from running its example against live data or completing an authenticated operation within the session. Event 94: ```text Blocked on one thing:** running the example against live data requires an API key, and signup (`https://matrix.blocksize.capital/auth/open/sign-up`) is a browser flow I can't complete for you ``` Event 41: ```text As a user of Blocksize, you can manage your subscription details by logging into the customer portal:\n\n[matrix.blocksize.capital](https://matrix.blocksize.capital/auth/open/sign-up) ``` #### Suggested Changes - **Publish a demo or sandbox API key for unauthenticated testing**: The docs mention a 'demo API key' is used in the browser Playground (per the /playground page metadata seen during crawling), but no demo key is available for script-based testing without the browser UI. Exposing a rate-limited demo key via api-docs.json or llms.txt would let automated agents validate authenticated flows (e.g. vwap_subscribe, authentication_logon) end-to-end without a manual signup step. Verify by having a non-interactive client authenticate and pull a live snapshot using the published demo key. Event 19: ```text description:"Test Blocksize market data in your browser with a demo API key. Stream live feeds, send curated JSON-RPC requests, inspect readable results, and view the raw response." ``` ### Task given to each agent Help me build a simple example using Blocksize. 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, methodology, pricing, API spec, MCP server and site index. ``` - **Pass** — llms.txt provides navigation guidance ```text llms.txt organizes content with sections, a which-product table and site index. ``` - **Pass** — llms.txt mentions offered API, MCP, and skills ```text llms.txt mentions API docs, api-docs.json spec, and the MCP server for agents. ``` - **Pass** — A compact guide representation exists ```text llms.txt is a standalone Markdown guide covering products, pricing, methods and site index. ``` - **Pass** — A focused guide is directly retrievable ```text llms.txt and SKILL.md are directly retrievable Markdown guides with concrete steps. ``` - **Pass** — Equivalent instructions fit a token budget ```text llms.txt is 4434 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 Remote MCP quickstart gives concrete install steps for Cursor, Claude, ChatGPT and local server. ``` - **Pass** — Install and next-step links resolve ```text Fetched quickstart, auth, OpenAPI, MCP and API docs links all returned HTTP 200. ``` ### Onboarding - **Pass** — Docs lead to a relevant quickstart ```text llms.txt and MCP quickstarts give concrete first steps: connect endpoint, authenticate, call vwap_subscribe. ``` - **Pass** — Installation commands are extractable ```text Remote MCP quickstart shows uv venv, uv pip install -e ".[dev]", python -m src.mcp_server. ``` - **Pass** — Code examples are available without interaction ```text Quickstarts include copyable JSON-RPC, curl, and Cursor mcp.json examples without interaction. ``` - **Pass** — Prerequisites and auth boundaries are explicit ```text llms.txt states authentication_logon, X-Api-Key/Bearer headers, and API key signup at matrix.blocksize.capital. ``` ### Pricing - **Failed** — Agents identify pricing and its assumptions ```text 3 of 3 sessions were judged on pricing; 1 fell short. DeepSeek V4.1 Flash: Gave no cost figure for any paid plan. It listed tier limits and a free 14-day trial, then said dollar amounts only appear at sign-up, so no cost was stated with assumptions (seq 35, seq 69, seq 92, README.md) Kimi K3: Quoted €49/€299/€799 monthly and yearly prices tied to tier, active-feed/seat/history limits, 15% yearly saving and 14-day no-card trial, sourced from pricing page (seq 43, seq 109, README.md) Qwen 3.8 Max: Explained subscription tiers with documented limits and a 14-day free trial; said no public dollar prices exist after searching the site and bundle, and quoted no unsupported number (seq 41, seq 49, seq 59, seq 94) This behavioural item does not affect the fast grade. ``` - **Pass** — Pricing is readable without interaction ```text Pricing page renders all four tiers with prices and limits directly in fetched HTML. ``` - **Pass** — Prices are stated, not gated ```text Developer €49, Start-Up €299, Business €799 monthly stated publicly; Enterprise quoted. ``` - **Pass** — Pricing units and limits are explicit ```text Tiers list active feeds, endpoints, historical data, seats and support explicitly. ``` ### Activation - **Pass** — An API reference or OpenAPI spec is reachable ```text OpenAPI JSON at mcp.blocksize.info/openapi.json and api-docs.json document the market data API. ``` - **Pass** — An MCP server is documented and well-formed ```text Remote MCP server documented with URL, tool list, sessions, and client setup guides. ``` - **Pass** — A CLI install path is documented ```text Local MCP CLI install path documented with uv venv, pip install, and run command. ``` - **Skipped** — SDK packages resolve on their registries ```text No SDK or package registry lookup result supplied for a Blocksize developer package. ``` - **Pass** — Agent skills are published ```text Agent skill published at .well-known/agent-skills with index and SKILL.md. ``` [Full report data](https://www.ax-check.com/blocksize.info/report.json)