SandBase Harness

Name: SandBase Harness
Author: sandbaseai

by sandbaseaiversion 0.3.8i★ –iRuns on your computer

Registry nameio.github.sandbaseai/sandbase-harness

Install

Overview

Description from the maker (original English)

Stdio MCP bridge for SandBase Harness agents, sessions, turns, artifacts, and cancellation.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Other
You need to fill in: MANAGED_AGENTS_URL, MANAGED_AGENTS_API_KEY

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
You fill in yourself: MANAGED_AGENTS_URL, MANAGED_AGENTS_API_KEY

Values marked secret are keys to your account. Never share them or paste them into a chat.

You need

DockerDocker installed

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "sandbase-harness": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "MANAGED_AGENTS_URL",
        "-e",
        "MANAGED_AGENTS_API_KEY",
        "ghcr.io/sandbaseai/sandbase-harness-mcp:0.3.8"
      ],
      "env": {
        "MANAGED_AGENTS_URL": "your-value",
        "MANAGED_AGENTS_API_KEY": "your-value"
      }
    }
  }
}

Run this in your terminal

claude mcp add sandbase-harness --env MANAGED_AGENTS_URL=your-value --env MANAGED_AGENTS_API_KEY=your-value -- docker run -i --rm -e MANAGED_AGENTS_URL -e MANAGED_AGENTS_API_KEY ghcr.io/sandbaseai/sandbase-harness-mcp:0.3.8

Fill in the empty values before running it.

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "sandbase-harness": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "MANAGED_AGENTS_URL",
        "-e",
        "MANAGED_AGENTS_API_KEY",
        "ghcr.io/sandbaseai/sandbase-harness-mcp:0.3.8"
      ],
      "env": {
        "MANAGED_AGENTS_URL": "your-value",
        "MANAGED_AGENTS_API_KEY": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "sandbase-harness": {
      "type": "stdio",
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "MANAGED_AGENTS_URL",
        "-e",
        "MANAGED_AGENTS_API_KEY",
        "ghcr.io/sandbaseai/sandbase-harness-mcp:0.3.8"
      ],
      "env": {
        "MANAGED_AGENTS_URL": "your-value",
        "MANAGED_AGENTS_API_KEY": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

Values you fill in

MANAGED_AGENTS_URL required env
URL of the SandBase Harness runtime API.
MANAGED_AGENTS_API_KEY secret env
API key when the connected Harness runtime requires authentication.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account sandbaseai, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Otheri

More stars than 0% of the other 32686 servers in this category
Published to the registry more recently than 31% of the other 32686 servers in this category
Basic checks equal to or better than 100% of the other 32686 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is SandBase Harness safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

You need to fill in: MANAGED_AGENTS_URL, MANAGED_AGENTS_API_KEY

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.3.8) reached the registry 2 months ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Docker on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, Microsoft Exchange Online MCP

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README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

SandBase Harness

English | 中文

AI-readable project metadata: llms.txt · installation guide

A local-first runtime for AI agents. Sessions, sandboxed tools, memory, credentials, audit trails, and a built-in Console — all running on your machine or in your own infrastructure.

Why

Agent SDKs handle the model loop. Production agents need more: persistent sessions, tool governance, sandbox boundaries, credential handling, memory, auditability, and a UI for humans to inspect what happened. managed-agents is that runtime layer — not a visual workflow builder and not another model SDK.

Need	What Harness provides
Run generated code safely	Local, Docker, Kubernetes, and self-hosted worker sandboxes
Inspect long-running agents	Persistent sessions, resumable event streams, audit, and replay
Control tool access	MCP toolsets, credential vaults, permission policies, and approvals
Operate any model	OpenAI, Anthropic, MiniMax, and OpenAI-compatible providers, including DeepSeek V4
Keep infrastructure yours	Local-first SQLite and file storage with no required hosted control plane

Features

Claude Managed Agents-style /v1 API and local Console
SQLite metadata by default for agents, sessions, environments, credential vaults, memory stores, files, skills, and API keys — local file/skill bytes in the workspace state directory
Resumable Server-Sent Events for session replay and debugging
One active model provider boundary configured through Settings V2
Sandbox backends: local process, Docker (per-session containers), Kubernetes (kubectl exec/cp), self-hosted worker queue
MCP toolsets, permission policies, built-in tools, and skill packages
TypeScript SDK at managed-agents/sdk
Release gate: npm run release:check

Quick Start

Requirements: Node.js 22+, npm 10+, and a model provider API key (OpenAI, Anthropic, MiniMax, or any OpenAI-compatible endpoint). Docker is optional and only needed for Docker-backed sandboxes.

git clone --branch v0.3.8 --depth 1 https://github.com/sandbaseai/sandbase-harness.git

cd sandbase-harness npm ci npm run build mkdir ../my-agents && cd ../my-agents node ../sandbase-harness/dist/index.js init node ../sandbase-harness/dist/index.js start

init writes a workspace into the directory you run it from: an agent, a skills folder, and config.yaml, whose provider reference is the ${OPENAI_API_KEY} environment variable. start serves the API and the Console on http://127.0.0.1:3000.

Two steps finish the setup, both on Settings > Setup at http://127.0.0.1:3000/dashboard:

The provider. Paste your API key into the provider form and save. The page then reports that the saved configuration is not active yet, so restart the runtime — stop it with Ctrl+C and run the start command again, or use the restart button. A saved setting only takes effect at startup. If your provider is not in the list, choose the OpenAI-compatible vendor and set its base URL.
The model. In the Agent models panel, set the model ID your provider actually serves — deepseek-chat for DeepSeek, for example. An agent carries its own model ID, so the gpt-4o that init writes is not valid for every provider, and a wrong ID fails the turn with model_not_found.

Send the first message from the Console: open Sessions, create a session for the agent, and type into the composer. From a terminal it is one command:

node ../sandbase-harness/dist/index.js chat agent_assistant --message "hello" --tool-approval allow

chat sends that one message and exits once the turn settles; without --message it keeps the session open and streams until you interrupt it. --tool-approval allow preauthorizes the tool calls the agent may make, which the init template otherwise parks for approval and waits for a person to answer; see CLI.

The unscoped managed-agents name on npm is not this project. Until an official scoped package is announced in this repository, install only from the tagged GitHub source release shown above. Do not run npx managed-agents or npm install managed-agents.

Try it in Codespaces

The included development container installs dependencies and builds the runtime. When the terminal is ready, start the server on the forwarded port:

node dist/index.js start --host 0.0.0.0

Open the forwarded SandBase Harness Console port, then configure a model in Settings > Setup. Codespaces usage may be billed by GitHub; the local quick start above remains free and keeps all runtime data on your machine.

Screenshots

Console overview	Settings	API reference

Use the Official SDK

The runtime answers its own /v1 API on that same port, and an official Anthropic TypeScript SDK client drives it unchanged: point the client's baseURL at the runtime, give it the runtime API key, and the quickstart in examples/official-sdk runs a whole turn — message, tool call, tool result, final reply — against it. That example is executed on every pull request by tests/conformance/official-sdk-quickstart.test.ts, so the compatibility it describes is compatibility that is tested rather than claimed.

The same surface is specified in docs/api.md, and this repository's own TypeScript SDK is documented under SDK below.

CMA compatibility

Coverage of the published Claude Managed Agents contract is declared entry by entry in src/core/capabilities/matrix.ts: of the official SDK's route surface (110 method/path pairs as of SDK 0.132.1), 90 routes are mounted and 20 refuse by name; no route is deferred. Partial and Unsupported entries always name their reason.

The table below is generated by npm run docs:compat, and a contract-honesty test fails when it drifts from the matrix.

Full compatibility table (generated)

Area	Official capability	Status	Notes
headers	`compatibility-header-admission`	Partial	Version, beta, and mutual-exclusion rules are enforced for any request that carries a compatibility header. A request with no compatibility header is accepted as a local caller, which the published contract does not define; this header-free path is a deliberate local-first extension for a self-hosted single-tenant runtime, recorded as such in the headers contract §4, and it is why this entry stays partial.
headers	`extension-namespace-exclusion`	Supported
pagination	`opaque-cursors`	Partial	A collection's envelope follows the mount: the operations router serves `/v1` with `{data, prev_page, next_page}` and its `/v1/x` mirror with the local `{data, has_more, first_id, last_id}`, chosen through one pager so no handler emits both spellings, and cursors that are readable base64url JSON rather than opaque binary. Every canonical `/v1` collection serves the canonical envelope, with no exceptions: the complete-set listings carry `{data, prev_page: null, next_page: null}` and the windowed ones carry a followable cursor — `/v1/sessions` pages by number under `{order, created_at bounds, page}` and rejects a cursor replayed under another ordering or creation window, `/v1/sessions/{id}/events` carries `{order, filter, after_id}`, `/v1/skills` and the credential audit listings use `{offset, filter}` — so a cut page says so instead of looking complete. The one listing that is neither shape is `/v1/environments/{id}/work-items`, a windowed extension that adds a `counts` object and is named in the contract.
pagination	`cursor-query-binding`	Supported
errors	`structured-error-envelope`	Supported
agents	`agent-crud`	Supported
agents	`model-object-profile`	Partial	String and object model forms parse field by field. `effort` and `speed` are stored, returned by the read projection (the agent read, the version read, and the session snapshot), and executed on the Anthropic provider under a model capability table — `effort` becomes `output_config.effort`, `fast` becomes `speed: "fast"` with the fast-mode beta, and adaptive-thinking models receive `thinking: {type: "adaptive", display: "omitted"}`; a listed model refused a level or speed it cannot take fails admission, an unknown model id or non-Anthropic provider sends nothing, and a deployment's own `reasoning_effort` model setting is operator-level and separate. `inference_geo` is refused by name with `unsupported_model_field` because this runtime has no inference-geography control; and a canonical `multiagent` roster is refused by name rather than executed.
agents	`multiagent-roster`	Unsupported	In scope but not implemented (decisions/0002): a canonical `multiagent` block (`multiagent_20261001` or any other shape) is refused by name on both agent create and agent update, because no thread, subagent, workflow, or advisor surface exists to honour it and the surface is a protocol of its own this runtime does not implement; accepting it would let a caller believe delegation or workflow runs are in effect. Local delegation is registered separately as an extension.
agents	`local-delegation-subagent`	Supported
sessions	`session-lifecycle`	Supported
sessions	`initial-events`	Supported
sessions	`prompt-caching`	Supported
sessions	`session-update`	Supported

| budget | session-budget | Partial | Consumption is priced in integer microcents from the append-only log, and a session may declare a max_list_cost ceiling at creation. The builtin loop checks the ceiling inside a turn: the step that crossed the cap is the last one, the session idles with stop_reason budget_reached and a session.usage immediately before it, and an accepted budget update or removal resumes the session on its own — a tool call the ceiling stranded is settled so the resumed turn sees a paired transcript. At the ceiling the next work-starting event is refused with budget_reached while events that settle work already in flight are still accepted, so the next model request does not start; a declared outcome's revision loop reads the same spend and stops at the ceiling too, closing the outcome with result budget_reached rather than starting another grading p

Only the beginning is shown; read the rest in the repo

SandBase Harness

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

Values you fill in

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Otheri

Common questions

Alternatives

Spec Driven Development

Remote Desktop Commander

Microsoft Exchange Online MCP

README from the maker

SandBase Harness

Why

Features

Quick Start

Try it in Codespaces

Screenshots

Use the Official SDK

CMA compatibility