Zearch

Answers you can check, inside any MCP client.

@zearchcomputer/mcp connects Claude, Cursor, VS Code and other Model Context Protocol clients to Zearch. Ask a question and you get an answer whose every paragraph was checked against the source it cites, with the exact passage Zearch read. Or check text your own model wrote against sources you already have.

Status: early. The Zearch API is not open to everyone yet.

How an answer is made

flowchart LR

Q([Question]) --> S[Search] S --> J1[Jev selects passages] J1 --> W[Writer drafts from those passages only] W --> J2[Jev checks each paragraph] J2 -->|supported| A([Cited answer]) J2 -->|not supported| E([The source passage itself])

Jev is TypeSafe AI's evidence model. When a paragraph can't be supported it is cut, and when nothing survives you get the best source passage instead of a guess (answer_type: "excerpt").

Tools

Errors are never charged. A run that can only return a source passage costs half.

Progress. research streams its stages (*Searching the web → Choosing the most relevant evidence → Checking each claim against its source*) as MCP progress notifications, so clients that show progress show what Zearch is doing.

Answer view. In clients that support MCP Apps, research, get_run and verify render an inline card: the answer with citation chips, source cards with the excerpt Jev read, an *Open* button for each source, and follow-up suggestions. It follows the client's light or dark theme. Other clients get the same content as text. Set ZEARCH_UI=0 to turn it off.

Resources. zearch://runs/{id} (a run as Markdown; your recent runs are listed), zearch://pricing.

Prompts. research_brief (a cited brief from deep research), fact_check (find sources for a draft, then verify it), compare (a table with a citation in every cell).

Install

You need a Zearch API key (zk_live_…). Create one in the Zearch app under Account → API keys.

Claude Code

claude mcp add zearch --env ZEARCH_API_KEY=zk_live_your_key -- npx -y @zearchcomputer/mcp

Claude Desktop

In *Settings → Developer → Edit config*, add:

{

"mcpServers": { "zearch": { "command": "npx", "args": ["-y", "@zearchcomputer/mcp"], "env": { "ZEARCH_API_KEY": "zk_live_your_key" } } } }

Cursor

.cursor/mcp.json (project) or ~/.cursor/mcp.json (global): the same mcpServers block as Claude Desktop.

VS Code

.vscode/mcp.json, which prompts for the key instead of storing it:

{

"inputs": [{ "type": "promptString", "id": "zearch-key", "description": "Zearch API key", "password": true }], "servers": { "zearch": { "type": "stdio", "command": "npx", "args": ["-y", "@zearchcomputer/mcp"], "env": { "ZEARCH_API_KEY": "${input:zearch-key}" } } } }

Run from source

git clone https://github.com/zearchcomputer/zearch-mcp

cd zearch-mcp npm ci && npm run build

Then use node /absolute/path/to/zearch-mcp/dist/index.js as the command in any config above, instead of npx -y @zearchcomputer/mcp.

Remote (HTTP) mode

npx -y @zearchcomputer/mcp --http --port 8787            # http://127.0.0.1:8787/mcp

Every request uses the caller's own key, sent as Authorization: Bearer zk_live_…; the server stores no keys. ZEARCH_API_KEY is used as a fallback only when the server listens on loopback, so a public deployment can't spend the operator's credits for someone else. GET /healthz reports liveness.

To serve on a public interface, bind it and list the hostnames you serve, so requests with other Host headers are refused:

npx -y @zearchcomputer/mcp --http --host 0.0.0.0 --port 8080 --allowed-hosts mcp.zearch.computer

A Dockerfile is included for this.

Configuration

Reliability

• Each research call carries an idempotency key, reused across retries, so a retried request never runs or charges twice.
• Network failures, 5xx responses and per-minute rate limits are retried with backoff that honours Retry-After. Out-of-credit, auth and validation errors are not retried; they come back as a tool error that says what to do next.
• If a research stream drops, the server reads the finished run instead of failing.
• Cancelling a tool call in the client cancels the request to Zearch.
• Logs go to stderr. Keys are never logged.

Development

npm ci

npm test # builds, then runs the tests against a local mock of the Zearch API

Tests make no network calls beyond localhost and spend no credits. The view is a single dependency-free HTML file in src/ui/answer.html.

The server is built on the MCP TypeScript SDK v2 (protocol revision 2026-07-28, with 2025-era clients still served) and talks to the Zearch API.

Security

Report vulnerabilities privately through GitHub security advisories. See the security policy.

License

MIT