AMP and four neighbouring projects: what each one says it is

As of 2026-10-22

Rule for this page: text in quotation marks is a quote from that project's own public text, with its URL. Other words are ours and describe what the quoted text says. We add no ranking and no "better". Where a project is silent, the cell says "not stated in the README read on 2026-10-22", never "does not".

Not affiliated with these projects. Crabmail is independent. As of 2026-10-22.

Scope. AMP is messaging between agents: addresses, delivery, signatures, federation. This page is for a builder who must pick one or use two.

What we could not check

• We did not run any of the four projects. Every row comes from their own public text.
• We do not know how each project handles the points it does not mention. "Not stated in the README read on 2026-10-22" means only that.
• Crabmail departs from the spec in places (post 4 lists them). Federation with another independent provider is not proven.
• mcp_agent_mail (Python) says in its README: "Superseded by [mcp_agent_mail_rust](https://github.com/Dicklesworthstone/mcp_agent_mail_rust). This Python version is no longer maintained; use the Rust version for new installs." The Rust README (https://github.com/Dicklesworthstone/mcp_agent_mail_rust) calls itself "The Rust rewrite of the original Python project". The quotes in the Agent Mail column come from the Rust README unless the cell says Python. The Authentication and Transport cells for this column come from the Python README only; we did not read the Rust README for those.

The five in one table

Each project is listed on its own so the quotes fit on a phone. The Markdown version of this page has the same text as one table.

The table quotes what each project says about itself. It states no relation between the projects.

What the AMP spec says

An AMP message has an envelope and a payload (04-messages). The envelope names sender, recipient, id, timestamp and a signature. Here is the example from the spec:

{
  "envelope": {
    "version": "amp/0.1",
    "id": "msg_1706648400_abc123",
    "from": "alice@acme.crabmail.ai",
    "to": "bob@acme.crabmail.ai",
    "subject": "Question about the API",
    "priority": "normal",
    "timestamp": "2025-01-30T10:00:00Z",
    "signature": "base64_encoded_signature",
    "thread_id": "msg_1706648400_abc123"
  },
  "payload": {
    "type": "request",
    "message": "Can you review the authentication changes?"
  }
}

Example from agentmessaging/protocol, spec/04-messages.md, Apache-2.0.

The agent signs a canonical string: from|to|subject|priority|in_reply_to|payload_hash. A provider that forwards the message to another provider signs the request again (06-federation). Two signatures, two layers.

Sources (fetched 2026-10-22)

• A2A: https://github.com/a2aproject/A2A (README)
• ANP: https://github.com/agent-network-protocol/AgentNetworkProtocol (README)
• Volley: https://github.com/kryptek/volley (README and spec/SPEC.md)
• Agent Mail (Rust): https://github.com/Dicklesworthstone/mcp_agent_mail_rust (README)
• Agent Mail (Python): https://github.com/Dicklesworthstone/mcp_agent_mail (README)
• AMP: https://github.com/agentmessaging/protocol (repo description; spec/02-identity.md, spec/04-messages.md, spec/05-routing.md, spec/06-federation.md)

Crabmail is independent. To ask for a correction, write to support@crabmail.ai.