Helixar Security vs Kastell
A side-by-side look at the Helixar Security and Kastell MCP servers: transport, auth, tools, quality signals, and the config to install either one in Claude, Cursor, Windsurf or VS Code.
Verdict: choose Helixar Security for security work over a hosted endpoint; choose Kastell for security as a local process. You can also run both side by side in one mcpServers block.
Which MCP server should you choose?
Choose Helixar Security when
- You need dedicated capabilities in the Security domain.
- You prefer a remote HTTP/SSE transport.
- You want tools like
helixar_inspect_mcp, helixar_hdp_validate.
Choose Kastell when
- You need dedicated capabilities in the Security domain.
- You prefer a local stdio subprocess transport.
- Its auth model fits you: No auth required.
Feature & specification comparison
Rows where the two servers differ are marked.
| Spec | ||
|---|---|---|
| Category | Security | Security |
| Quality signal | 56/100 · Good | 61/100 · Good |
| Install command | Confirmed | Confirmed |
| Transport | Remote HTTP/SSE | Local subprocess (stdio) |
| Auth | Not declared | No auth required |
| Pricing | Not declared | Free |
| Required env vars | None listed | None listed |
| Verified owner | Community listing | Community listing |
| GitHub stars | 0 | 60 |
| Directory activity | 0 views 0 installs 0 upvotes | 5 views 0 installs 0 upvotes |
| Tools | 2 | Not listed |
| Full listing | View Helixar Security | View Kastell |
Tools & capabilities
Helixar Security tools 2
helixar_inspect_mcpScan an MCP server (URL or raw manifest JSON) against Helixar's Sentinel detection rules. Returns risk score, findings, and a Claude-generated security brief. Quick mode is free + authless (top 8 rules); deep mode runs all 26 rules with an api_key.helixar_hdp_validateValidate an HDP delegation chain against IETF draft-helixar-hdp-agentic-delegation-00. Surfaces scope escalations, depth violations, expired hops, missing signatures. Every output cites the IETF draft and Zenodo DOI.
Kastell tools
No tool names declared yet. Check the project README from the listing page.
Ready-to-paste client configs
Paste either block (or both) into your client config, e.g. claude_desktop_config.json or ~/.cursor/mcp.json. We only show a config when the install command is confirmed.
Helixar Security
{
"mcpServers": {
"helixar-security": {
"url": "https://mcp.helixar.ai/mcp"
}
}
}
Kastell
{
"mcpServers": {
"kastelldev-kastell": {
"command": "npx",
"args": [
"-y",
"kastell"
]
}
}
}
Frequently asked questions
Helixar Security is categorized under Security and uses a remote HTTP/SSE transport. Kastell belongs to Security and uses a local stdio subprocess. Pick Helixar Security for security work and Kastell for security.
Copy the mcpServers block from the config section on this page into your client's config (for example claude_desktop_config.json or ~/.cursor/mcp.json), then fully restart the client.
Helixar Security has no declared pricing — check the project's own site. Kastell is listed as free. Auth: no auth required. If a server needs environment variables such as API keys, define them under the env key in your client's MCP config.
Yes. MCP clients support multiple servers: add helixar-security and kastelldev-kastell as separate keys in the same mcpServers object, and your assistant will call tools from either one.
On AllMCPs, Helixar Security has a quality signal of 56/100 (Good) with 0 views, 0 installs and 0 GitHub stars. Kastell has 61/100 (Good) with 5 views, 0 installs and 60 GitHub stars.