opena2a mcp

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

Usage

Subcommands

Options

Config File Locations

The audit subcommand scans these locations for MCP server configurations:

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

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 OpenA2A trust data
• Identity age: Older, stable identities receive a slight trust bonus

The registry lookup in mcp audit and mcp verify goes to https://api.oa2a.org unless registry.url is set in ~/.opena2a/config.json to another host. A value that names a retired host, registry.opena2a.org or api.opena2a.org, is read as unset, so the lookup still goes to https://api.oa2a.org. To use a private registry, set it there, for example "registry": { "url": "https://registry.example.com" }. The URL must use HTTPS; plain HTTP is accepted only for localhost, and with any other URL the lookup fails and no trust score is returned. opena2a config has no action that sets this key, so edit the file; opena2a config show prints the URL the commands will use. The other opena2a commands that contact the registry, such as trust, verify and detect, read the same key. opena2a admin is the exception: it sends the registry admin key, so it ignores registry.url and goes to https://api.oa2a.org unless another host is named on its command line.

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.

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