opena2a mcp

MCP server identity management. Audit, sign, and verify MCP server configurations.

Usage

opena2a mcp [subcommand] [server] [options]

Subcommands

Subcommand	Description
`audit`	Discover and list MCP server configurations across all tools. This is the default when no subcommand is given.
`sign <server>`	Create an Ed25519 identity for a named MCP server. Generates a keypair and stores it in .opena2a/mcp-identities/.
`verify <server>`	Verify an MCP server identity signature and display trust score.

Options

Flag	Description
`--dir <path>`	Target directory. Default: current working directory.
`--format <text\|json>`	Output format.
`--ci`	CI mode. Non-interactive output.
`--verbose`	Show identity file paths and full commands when truncated.

Config File Locations

The audit subcommand scans these locations for MCP server configurations:

Tool	Config Path
Claude Code	`~/.claude/mcp_servers.json`
Cursor	`~/.cursor/mcp.json`
Windsurf	`~/.config/windsurf/mcp.json`
VSCode extensions	`~/.vscode/extensions/*/mcp.json`
Project-local	`./mcp.json, ./.mcp.json`

Identity Signing

When you sign an MCP server, the CLI generates an Ed25519 keypair and stores it in.opena2a/mcp-identities/<server>.json. The identity file contains:

Server name and creation timestamp
Ed25519 public key (hex-encoded)
Signature over the server configuration
Algorithm identifier

Examples

# Discover all MCP server configs

opena2a mcp

# Sign an MCP server identity

opena2a mcp sign filesystem

# Verify a signed server

opena2a mcp verify filesystem

# Audit with verbose output (shows file paths and full commands)

opena2a mcp audit --verbose

# JSON output for CI

opena2a mcp audit --ci --format json

Example Workflow

# 1. Discover what MCP servers are configured
opena2a mcp

# 2. Sign servers you want to track
opena2a mcp sign filesystem
opena2a mcp sign playwright

# 3. Verify signatures later
opena2a mcp verify filesystem

# 4. Run detect to see full picture (signed servers show as verified)
opena2a detect

Trust Scores

When verifying a signed MCP server, the command calculates a trust score based on several factors:

Signature validity -- Whether the Ed25519 signature matches the current configuration
Configuration drift -- Whether the server config has changed since signing
Registry lookup -- Whether the server is known in the OpenA2A Trust Registry
Identity age -- Older, stable identities receive a slight trust bonus

Use the --registry flag to point to a custom Trust Registry instance for private or enterprise environments.

Expected Audit Output

$ opena2a mcp audit --verbose

MCP Server Audit
=================

Claude Code (~/.claude/mcp_servers.json):
  filesystem     npx @anthropic/mcp-filesystem /home/user
  playwright     npx @anthropic/mcp-playwright

Cursor (~/.cursor/mcp.json):
  github         npx @modelcontextprotocol/server-github

Project-local (./mcp.json):
  custom-api     node ./servers/api-server.js

Summary: 4 servers across 3 config files
Signed:  1 (filesystem)
Unsigned: 3

Error Handling

If no MCP configuration files are found, the audit subcommand reports "No MCP servers configured" and exits with code 0. When signing a server that does not exist in any configuration, the command lists discovered servers and exits with code 1. If the identity directory (.opena2a/mcp-identities/) is not writable, the sign subcommand reports a permission error. Verification of a server that has never been signed reports "No identity found" with instructions to sign it first.

detect guard shield trust