Fabric Verify — Claude Code MCP server: a signed log of agent actions
Signs a short record of each agent action on your machine and publishes it to a public log, then hands you a proof anyone can check offline.
claude mcp add --transport http fabric-verify https://mcp.augmentev.com/mcpWhat Fabric Verify does
Call record_action and the server signs one record with the agent's own key, locally, before adding it to the Fabric Verify public log. get_proof later returns a proof that the record existed unchanged by a given time. It says nothing about whether the record's contents are true, only that the entry has not been altered.
Your text never leaves the machine. What goes out is a salted fingerprint plus the signature. Every entry in the public log shows the agent name, key name, action kind, timestamp and public key forever, so keep personal data out of FABRIC_AGENT and FABRIC_KID. A record costs $0.005 from prepaid credit; the other tools cost nothing. The fvk_… credit key appears once after card payment, so put it in a password manager.
Node.js 20 or newer is required. The agent key lives at FABRIC_HOME/agent-ed25519.pem and is worth backing up, because a key name is bound to one key permanently — lose the file and you must set a fresh FABRIC_KID. Pin an exact version for production agents, for example npx -y @augmentev/[email protected]; the package carries npm-shrinkwrap.json, so its dependencies stay fixed too.
What it helps with
- prove an agent action happened without exposing the underlying text
- give a third party a proof they can verify offline
- cap what the server can spend during one session
- retry a failed record call without paying twice
- check a record against the published log keys offline
Example prompts for the agent
- Record a deploy action with
record_action, kind=deploy, and a short summary - Fetch the proof for record index 42 with
get_proof - Show remaining credit and this session's spend with
check_balance
How to install Fabric Verify
1Platform CLI: remote server
claude mcp add --transport http fabric-verify https://mcp.augmentev.com/mcp2Platform CLI
claude mcp add --env FABRIC_CREDIT_KEY=<FABRIC_CREDIT_KEY> --env FABRIC_AGENT=<FABRIC_AGENT> --env FABRIC_MAX_SPEND_USD=<FABRIC_MAX_SPEND_USD> --transport stdio fabric-verify -- npx -y @augmentev/fabric-verify-mcpReplace <…> with your own values
1Platform CLI: remote server
codex mcp add fabric-verify --url https://mcp.augmentev.com/mcp2Platform CLI
codex mcp add fabric-verify --env FABRIC_CREDIT_KEY=<FABRIC_CREDIT_KEY> --env FABRIC_AGENT=<FABRIC_AGENT> --env FABRIC_MAX_SPEND_USD=<FABRIC_MAX_SPEND_USD> -- npx -y @augmentev/fabric-verify-mcpReplace <…> with your own values
Config file
{
"mcpServers": {
"fabric-verify": {
"url": "https://mcp.augmentev.com/mcp"
}
}
}{
"mcpServers": {
"fabric-verify": {
"command": "npx",
"args": [
"-y",
"@augmentev/fabric-verify-mcp"
],
"env": {
"FABRIC_CREDIT_KEY": "<FABRIC_CREDIT_KEY>",
"FABRIC_AGENT": "<FABRIC_AGENT>",
"FABRIC_MAX_SPEND_USD": "<FABRIC_MAX_SPEND_USD>"
}
}
}
}Replace <…> with your own values
Config file
{
"servers": {
"fabric-verify": {
"type": "http",
"url": "https://mcp.augmentev.com/mcp"
}
}
}{
"servers": {
"fabric-verify": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@augmentev/fabric-verify-mcp"
],
"env": {
"FABRIC_CREDIT_KEY": "<FABRIC_CREDIT_KEY>",
"FABRIC_AGENT": "<FABRIC_AGENT>",
"FABRIC_MAX_SPEND_USD": "<FABRIC_MAX_SPEND_USD>"
}
}
}
}Replace <…> with your own values
1Platform CLI: remote server
gemini mcp add -t http fabric-verify https://mcp.augmentev.com/mcp2Platform CLI
gemini mcp add -e FABRIC_CREDIT_KEY=<FABRIC_CREDIT_KEY> -e FABRIC_AGENT=<FABRIC_AGENT> -e FABRIC_MAX_SPEND_USD=<FABRIC_MAX_SPEND_USD> fabric-verify npx -y @augmentev/fabric-verify-mcpReplace <…> with your own values
Step by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about Fabric Verify
How do I install Fabric Verify in Claude Code?
For stdio: `claude mcp add --env FABRIC_CREDIT_KEY=<FABRIC_CREDIT_KEY> --env FABRIC_AGENT=<FABRIC_AGENT> --env FABRIC_MAX_SPEND_USD=<FABRIC_MAX_SPEND_USD> --transport stdio fabric-verify -- npx -y @augmentev/fabric-verify-mcp. An HTTP option also exists: claude mcp add --transport http fabric-verify https://mcp.augmentev.com/mcp`.
What does Fabric Verify do?
It signs records of agent actions with the agent's key on your own machine and appends them to a public log. On request it returns a proof that can be verified offline.
How much does recording an action cost?
record_action costs $0.005 per record, taken from prepaid credit. get_proof, check_balance and buy_credit_link are free.
