# costheta

Hooks your agent up to a remote source of verifiable physical randomness: a free beacon plus paid signed decisions.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI
- Author: costhetadev
- License: MIT · policy=link-only · description only; the file stays with the author
- Source: https://github.com/costhetadev/costheta-verify
- Updated: 2026-08-16
- HTML: https://affpapa.org/en/nevibecode/mcp/costheta

## What it does

costheta is a remote MCP server that hands your agent values derived from cosmic-ray detections. The beacon tier is free; signed decisions are paid. It lives at `https://costheta.dev/mcp`, so nothing runs on your machine.

A public verifier, `costheta-verify`, checks the canonical hash of a certificate body along with its Ed25519 (RFC 8032) and ML-DSA (FIPS 204) signatures, comparing them against the public keys at `costheta.dev/keys`. Certificate format v0.3 is laid out in the federation proposal. The verifier code has not been published yet.

If you need randomness you can show to a third party, this is worth a look. For shuffling fixtures in a test suite, plain `Math.random()` does the job and costs nothing.

## Requirements
- Remote server: `https://costheta.dev/mcp`

## Install

### Claude Code (native platform)

**Platform CLI: remote server**
```bash
claude mcp add --transport http costheta https://costheta.dev/mcp
```

### Codex

**Platform CLI: remote server**
```bash
codex mcp add costheta --url https://costheta.dev/mcp
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "costheta": {
            "url": "https://costheta.dev/mcp"
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "costheta": {
            "type": "http",
            "url": "https://costheta.dev/mcp"
        }
    }
}
```

### Gemini CLI

**Platform CLI: remote server**
```bash
gemini mcp add -t http costheta https://costheta.dev/mcp
```

## When to use it
- get random values that can be checked against a published key
- sign an agent decision with Ed25519
- match a certificate body hash to a public key
- add a physical randomness source to an agent with no local dependencies
- verify an ML-DSA signature per FIPS 204

## Example prompts
- Pull a random beacon value from costheta
- Verify this decision certificate against the keys at costheta.dev/keys
- Request a signed decision from costheta

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md