Provides an MCP server that Amazon Alexa+ clients can connect to over Streamable HTTP, enabling voice-style questions about CSV data with grounded facts, column listing, fact queries, and ECharts chart suggestions.
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type @ followed by the MCP server name and your instructions, e.g., "@ChartKeep MCP what's our best-selling region?"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
Self-hosted MCP server plus a web page that acts as an Alexa+ client. Ask a spreadsheet a question in the voice you would use on Alexa. The server computes facts from the CSV first, then answers. Charts are ECharts JSON returned by a tool, not guessed in the browser.
Built for the Amazon Developer Hackathon 2026 Alexa+ track. Amazon's Alexa+ MCP Toolkit and Web Simulator are partner-preview only, so this repo uses the path the FAQ allows: a Streamable HTTP MCP server (spec 2025-11-25) and a web client that sends initialize, tools/list, and tools/call.
No Amazon private SDK. No API keys. The sample table never leaves your machine.
Needs Node 20+ and npm. Bun is not required.
npm install
npm run devThen open http://127.0.0.1:5173.
That starts two processes:
Process | URL |
MCP server (Streamable HTTP) |
|
Alexa+ simulator (Vite) |
|
The simulator proxies /mcp to port 8787 so the browser does not have to fight CORS during the demo. Health check: http://127.0.0.1:8787/health.
Related MCP server: mcp-csv-database
The page connects and the MCP badge turns live. The wire log shows initialize (2025-11-25) and tools/list.
retail-sales.csv loads through load_dataset (36 rows of cafe sales by quarter, region, and product).
Click a voice chip, or type Alexa, what's our best-selling region?.
The transcript shows the tool call, then a spoken answer. If the question wants a chart, the paper plate on the right renders the ECharts spec from the tool result.
Upload any other CSV the same way. list_columns, query_facts, and suggest_chart keep working on the new table.
Tool | What it does |
| Load |
| Name, inferred kind, samples, null count |
|
|
| ECharts option JSON plus a one-line insight |
| Voice-style Q&A. Facts first. Numbers that are not in the table or the stats get dropped |
There is also a dataset://current resource and a voice-sales-brief prompt.
The grounded-facts idea comes from plotkeep: compute min/max/change/growth in code, then write the sentence from those numbers.
Alexa+ talks to brand add-ons over MCP Streamable HTTP. This repo does the same handshake a real Alexa+ client would:
simulator (this web page)
POST /mcp initialize → MCP-Session-Id
POST /mcp notifications/initialized → 202
POST /mcp tools/list
POST /mcp tools/call name=ask_about_data | suggest_chart | …Responses are JSON (enableJsonResponse: true). The client also parses text/event-stream if a server streams SSE, which the spec requires.
When partner tooling opens up, point Alexa+ at a public HTTPS URL for /mcp. Until then, this page is the client.
samples/retail-sales.csv bundled cafe sales
server/ Node + TypeScript MCP server
src/index.ts Express + StreamableHTTPServerTransport
src/createServer.ts tool / resource / prompt registration
src/csv.ts quoted CSV, kinds
src/facts.ts series stats + contradiction check
src/query.ts aggregates
src/chart.ts ECharts specs
src/ask.ts voice-style intent → facts → answer
simulator/ Vite + React + TypeScript client
src/mcp/client.ts Streamable HTTP (JSON and SSE)
src/agent/router.ts utterance → tools/call
FRICTION.md hackathon friction log
DEMO.md ≤3 minute video scriptStack: @modelcontextprotocol/sdk 1.32 (spec 2025-11-25), Express 5, Zod 3, Vite 7, React 19, ECharts 5. MIT.
npm testCovers CSV parse, West as the top region, Butter Croissant as fastest growth, and a pie spec.
A local run is enough for the hackathon. Judges can clone and run the two commands above.
If you want a public URL later:
Keep the server on 127.0.0.1 unless you add auth. The MCP spec warns about DNS rebinding.
Tunnel with cloudflared (or similar) to expose /mcp as HTTPS.
Alexa+ production also wants OAuth 2.1 + PKCE. That is out of scope here because the partner console is not available to entrants.
No .env secrets are used. Do not add keys to the repo.
MIT © 2026 sherotree
This server cannot be deployed
Ask questions about a CSV in plain English and get answers, charts and cleaned data back.
Query your warehouse or a CSV with Claude/ChatGPT over MCP, governed by table-level ACL + audit.
Query, join, profile, clean and convert CSV/JSON/Parquet with server-side DuckDB over MCP.
The all-in-one data stack for agents. Upload files, run SQL, evolve tables, and render charts.
