Warrant MCP Server
by s0fractalio.github.s0fractal/warrantv0.9.0
Record an agent's decisions with reasons anyone can re-execute offline — verify recomputes them.
context tax
queued
security
queued
cold start
queued
freshness
Active8d ago
Install Warrant MCP server
Install in Claude Code
claude mcp add s0fractal -e WARRANT_KEY='<warrant-key>' -- uvx warrant-verifyInstall in Cursor
{
"mcpServers": {
"s0fractal": {
"command": "uvx",
"args": [
"warrant-verify"
],
"env": {
"WARRANT_KEY": "<warrant-key>"
}
}
}
}Add to ~/.cursor/mcp.json (global) or .cursor/mcp.json (project).
Install in Claude Desktop
{
"mcpServers": {
"s0fractal": {
"command": "uvx",
"args": [
"warrant-verify"
],
"env": {
"WARRANT_KEY": "<warrant-key>"
}
}
}
}Settings → Developer → Edit Config (claude_desktop_config.json), then restart.
Install in VS Code
{
"servers": {
"s0fractal": {
"type": "stdio",
"command": "uvx",
"args": [
"warrant-verify"
],
"env": {
"WARRANT_KEY": "<warrant-key>"
}
}
}
}Add to .vscode/mcp.json in your workspace.
Install in Windsurf
{
"mcpServers": {
"s0fractal": {
"command": "uvx",
"args": [
"warrant-verify"
],
"env": {
"WARRANT_KEY": "<warrant-key>"
}
}
}
}Add to ~/.codeium/windsurf/mcp_config.json.
Configuration
| Variable | Required | Secret | Description |
|---|---|---|---|
| WARRANT_STORE | — | — | Absolute path to the warrant store this server files into and verifies. Defaults to .warrants relative to the server process's working directory, which an MCP host does not guarantee. |
| WARRANT_KEY | — | yes | Ed25519 signing key. If unset, one is generated next to the store on the first filing and the result says so; any process that can read it can sign as this actor. |
| WARRANT_ACTOR | — | — | Actor id written into filed warrants. Defaults to mcp-client@<hostname>. |
Freshness
Active — last maintenance signal 8d ago. The newest of the signals below sets the band.
Last commit (default branch)
2026-10-01 · 8d ago · GitHub
Latest release
2026-08-01 · 2mo ago · GitHub · v0.9.0
Package published
no data · npm/PyPI
Registry entry updated
2026-08-01 · 2mo ago · official registry · v0.9.0
FAQ
›How do I install the Warrant MCP server in Claude Code?
Run: claude mcp add s0fractal -e WARRANT_KEY='<warrant-key>' -- uvx warrant-verify. For Cursor, VS Code, Claude Desktop and Windsurf, use the install tabs above.
›Does Warrant require an API key?
Yes. It expects WARRANT_KEY, of which 1 is a secret.
›Can I use Warrant as a remote (hosted) MCP server?
No hosted endpoint is published; it runs locally over stdio.
›Is Warrant in the official MCP registry?
Yes, as io.github.s0fractal/warrant.