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Helio

Govern MCP tool calls with policies, approvals, budgets, evidence checks, rate limits, and audit records.

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Install Helio

Pick your client, then add it in one click or paste the config.

STDIONode.js
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "helio": {
      "command": "npx",
      "args": [
        "-y",
        "@gethelio/proxy"
      ]
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

We couldn’t confirm it starts correctly

The install command installed and started the server, which then stopped for configuration (such as an API key) that our sandbox does not have — expected for servers that connect to your account.

npx -y @gethelio/proxy

No response to initialize.

This is an experimental automated check and can have false negatives — missing environment variables, a slow cold install, etc. It doesn’t necessarily mean something’s wrong. Last checked 3d ago.

Overview

The Helio MCP server places a governance proxy between AI agents and MCP tools, deciding whether each call can proceed before forwarding it. It supports policy rules, prerequisites, evidence checks, approval workflows, cumulative budgets, rate and spend limits, and audit records. Helio keeps session identity, budgets, and evidence in the proxy rather than in agent context. Use it when MCP tools need controls that apply across agents, frameworks, and downstream systems.

Use cases

  • Govern destructive MCP operations
  • Require approval for high-value actions
  • Limit cumulative tool spending
  • Audit agent calls and policy changes
  • Check upstream tools before writing rules

Key features

  • Policy-based allow, deny, and approval controls
  • Prerequisite and evidence checks
  • Cross-tool budgets and spend limits
  • Audit records with configuration hashes
  • MCP upstream scanning
  • Optional Python SDK

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked Today

Recent health check succeeded.

4/4 checks healthy over the last 12d

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 12d ago via OSV.dev · @gethelio/proxy (npm)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

GitHub stars14Stargazers on the source repository.
npm downloads1.3kPackage downloads in the last 30 days.
Last commit2d agoMost recent push to the default branch.
Install checkRunsOur sandbox started it; it then asked for an API key or config.
Directory activity1 viewsConfig copies, upvotes, and views on AllMCPs.

How Helio works

What Helio does

The Helio MCP server governs tool calls between an AI agent and one or more MCP servers. It can allow or deny operations, request approval for selected actions, require an earlier tool call to succeed, and apply limits to rate or cumulative spend. Calls and policy activity are recorded in an audit trail, including the configuration hash associated with each decision.

The proxy is intended for controls that should not depend on instructions remaining in the model context. Session identity, budgets, and evidence remain outside the agent, so the agent cannot directly rewrite those governance values through normal tool-call state. Helio can also expose a dashboard and provides a scan command for inspecting an upstream server's tools before policies are written.

How it works

The Helio MCP server supports two integration paths. With proxy-only use, an MCP client connects to Helio instead of connecting directly to the upstream server, requiring no changes to the agent or MCP server. With the proxy and SDK path, a thin Python SDK can add evidence context and action dependencies to calls.

For stdio MCP servers, Helio owns the child process it starts and can provide structural enforcement on that path. For HTTP MCP servers, enforcement is network-based when the upstream's egress is controlled. Hook adapters can support frameworks that run tools in-process; these use a cooperative host-enforced grade in which the framework's hook gate enforces the decision while Helio supplies it.

The default local installation runs as the same user as the agent. In that arrangement, a same-user process may restart the proxy or alter its configuration and audit file. Running Helio under a separate user or in a container addresses that boundary described by the project documentation.

Setup and configuration

Install the runtime and bundled dashboard assets with npx @gethelio/proxy init. The command creates a helio.yaml file. Configure either a single upstream or a named upstreams list, then set the upstream URL and transport. Named upstreams are exposed through separate /mcp/<name> paths rather than merging their tool sets.

Initialization starts in audit-only mode: policies are commented out, the default is allow, and no calls are blocked. Add policy rules to enable enforcement. Use npx @gethelio/proxy scan --upstream <url> to list available tools, destructive-operation metadata, and arguments that can be matched by rules. The --sandbox option creates a sidecar layout for container-based deployments, while --demo creates sample traffic for exploring the interfaces.

Tools and capabilities

  • Match policy rules against tool-name globs.
  • Deny operations or route selected calls for approval.
  • Require prerequisite tool actions before dependent actions.
  • Set shared budgets across matching paid tools.
  • Apply rate and spend limits.
  • Attach evidence and dependency context through the optional Python SDK.
  • Record decisions, configuration hashes, and policy reload attempts.

Limitations and notes

The Helio MCP server does not automatically make a default installation restrictive; initialization records traffic but blocks nothing until policies are enabled. Enforcement strength depends on the transport or adapter path and on keeping the proxy configuration, secret, and audit store outside the agent's reach. The project documents the same-user local setup as a weaker boundary than an isolated deployment.

Read the full README View source on GitHub

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Frequently Asked Questions about Helio

Helio is an MCP server that connects AI agents to MCP servers through a governance proxy. Its main tools and controls include policy decisions, approval routing, prerequisite checks, evidence handling, rate and spend limits, budgets, upstream scanning, and audit records. It works without requiring changes to the agent or upstream MCP server.

Install it with `npx @gethelio/proxy init`. The package includes the proxy runtime and dashboard assets, and initialization creates a `helio.yaml` configuration file. Use `--sandbox` for a container sidecar layout or `--demo` to create sample traffic.

Add and enable the `policies` section in `helio.yaml`. Initialization leaves this section commented out, so the default setup allows calls and records them without blocking. Rules can match tool-name globs and apply denial, approval, prerequisite, rate, or spend controls.

Yes, Helio can govern multiple MCP servers through a named `upstreams` configuration. Each upstream is served through its own `/mcp/<name>` endpoint, and the tools are kept separate rather than merged. A single `upstream` configuration remains supported.

Yes, Helio can be placed between Cursor and an MCP server when Cursor connects through a supported MCP transport. The proxy-only path requires pointing the client at Helio instead of the upstream and does not require agent-code changes.

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