What it is
Everything is a reference server from the MCP project that tries to exercise every feature of the protocol. Its README is plain about it: it is "not intended to be a useful server, but rather a test server for builders of MCP clients". It is still maintained in the active modelcontextprotocol/servers repository, one of seven reference servers there alongside fetch, filesystem, git, memory, sequential thinking and time.
Version 2.0.0, released on 19 October 2026, moved it to the TypeScript SDK v2 and serves both protocol eras from one process: 2026-07-28 clients, which use server/discover and no session, and 2025-era clients, which use the initialize handshake. It needs Node.js 24 or later.
Run it with npx -y @modelcontextprotocol/server-everything over stdio, or from source with Streamable HTTP at http://localhost:3001/mcp. The HTTP+SSE transport remains for 2025-era clients only and is deprecated. The repo documents its architecture, startup, features and extension points.
Install
npx -y @modelcontextprotocol/server-everythingOur review
Everything matters more now than it did a year ago, because the protocol has split into two eras. The 2026-07-28 revision dropped the initialize handshake and sessions, so every client, gateway and proxy has to cope with servers of both kinds for some time. Version 2.0.0 answers both from one process, which makes it the natural fixture for checking a client against the new revision before production servers catch up.
Coverage is the point. Its 24 tools include a multi-step elicitation whose requestState is HMAC-signed and expires after ten minutes, task-based tools that exercise tasks/get, tasks/update and tasks/cancel, and a header tool that checks x-mcp-header mirroring and refuses a mismatched call with error -32020. Roots, sampling and logging, deprecated in 2026-07-28, are kept and labelled. The features document marks which era each behaviour belongs to, and reads as a usefully concrete diff of the spec.
Two tools need care outside a sandbox. get-env returns every environment variable of the server process as JSON, harmless in a CI container and a leak on a laptop where API keys live in the shell. gzip-file-as-resource fetches URLs, within size, time and domain limits. The Node 24 floor, raised days before 2.0.0, will also break CI images still on Node 22.
It is not a conformance suite. It shows what a correct server does and leaves grading your client to you, usually with the MCP Inspector open alongside. And the 2025-11-25 core task methods are no longer served, because SDK v2 removed the experimental layer they sat on, so a client built against that draft needs a different fixture.
Where it earns its place
An engineer adding 2026-07-28 support to an MCP client library
Test discovery, input_required round trips and tasks against a known-good server
Run npx -y @modelcontextprotocol/server-everything in CI and call trigger-multi-step-elicitation, simulate-research-query and trigger-url-elicitation from the client's tests. It costs nothing beyond moving the CI image to Node 24.
A platform team building an internal MCP gateway
Check that both protocol eras and their headers pass through the gateway intact
Start the Streamable HTTP build on localhost:3001/mcp behind the gateway, connect one 2025-era and one 2026-07-28 client, and use get-header-params to confirm Mcp-Param-Region survives the hop; a mismatch comes back as error -32020.
A developer-relations writer documenting MCP support in a host app
Show what each protocol feature looks like on the wire
Point the MCP Inspector at the server and capture real responses for structured content, resource links and progress notifications, using the features document as the reference. It saves building a mock server for screenshots.
Before you commit
- Setup
- npx -y @modelcontextprotocol/server-everything over stdio on Node.js 24+, with documented configs for Claude Desktop and VS Code; npm run start:streamableHttp from source serves http://localhost:3001/mcp. First tool call within a couple of minutes.
- Integrations
- 24 tools plus prompts, resources, subscriptions, logging and the tasks extension. Every tool is a test behaviour (echo, get-sum, trigger-sampling-request, trigger-long-running-operation); none connects to an outside account.
- Data and privacy
- No authentication and no account. get-env returns the full process environment and gzip-file-as-resource fetches URLs, so run it where the environment holds no secrets.
- Cost at scale
- Free and open source; the only cost is CI minutes. There is no paid API behind it.
- Limits
- Not a conformance test suite. HTTP+SSE serves 2025-era clients only and is deprecated, the 2025-11-25 core task methods are not served after the SDK v2 migration, and Node 22 is no longer supported.
What's good
- 24 tools covering both protocol eras from one process
- Maintained in the official servers repository with the SDK
- Features document marks each feature's era and deprecation
- stdio and Streamable HTTP from the same build
What's not
- get-env exposes the process's environment variables
- Needs Node.js 24 or later since 2.0.0
- Demonstrates behaviour but does not grade a client
- 2025-11-25 core task methods no longer served
Best for
Developers building or testing MCP clients, hosts and gateways, especially against the 2026-07-28 revision.
Alternatives
Everything (test server): common questions
- Is Everything (test server) worth it?
- Indispensable as a test fixture for MCP client authors and, by design, useless for anything else. We rate it 3.9 out of 5.
- How much does Everything (test server) cost?
- Free and open source.
- What are the downsides of Everything (test server)?
- get-env exposes the process's environment variables; needs Node.js 24 or later since 2.0.0; demonstrates behaviour but does not grade a client; 2025-11-25 core task methods no longer served.
- Who is Everything (test server) best for?
- Developers building or testing MCP clients, hosts and gateways, especially against the 2026-07-28 revision.
- How much does Everything (test server) cost for a team or in production?
- Free and open source; the only cost is CI minutes. There is no paid API behind it.
- Is Everything (test server) safe for company data?
- No authentication and no account. get-env returns the full process environment and gzip-file-as-resource fetches URLs, so run it where the environment holds no secrets.
- What are the best Everything (test server) alternatives?
- The closest alternatives we have reviewed are Time (reference server), Fetch (reference server) and Filesystem (reference server).
Answers checked Oct 23, 2026.