ARBITER — deterministic ordering for A2A agent handoffs

[ziolndr]

Built a runnable A2A integration for a problem that shows up as soon as an orchestrator has more than one valid agent available:

Which agent should receive the task?

ARBITER does not discover agents, generate candidates, authorize a handoff, or execute anything.

The caller already has:

• the current task/context
• a finite set of candidate Agent Cards, skills, proposals, routes, or next actions

ARBITER deterministically orders that supplied field against the current task.

The integration is live here:

https://github.com/ziolndr/arbiter-agent-routing

A2A extension/profile:

https://grip.fyi/agent-routing/a2a-extension/SPEC.md

Machine-readable extension:

https://grip.fyi/agent-routing/a2a-extension/extension.json

Runnable A2A router:

https://grip.fyi/agent-routing/a2a-router.mjs

Remote MCP:

https://api.grip.fyi/mcp

MCP identity:

fyi.grip/arbiter

Paid HTTP:

POST https://api.grip.fyi/v1/compare

Payment:

$0.01 USDC via x402 on Base

The intended handoff is:

A2A task/context
→ candidate Agent Cards
→ ARBITER ordering
→ existing local policy / authorization
→ handoff

There is also an optional community extension/profile URI:

https://grip.fyi/agent-routing/a2a-extension/v1

The goal is not to replace A2A discovery or trust/security mechanisms. It is to provide a deterministic ordering step once the client already has multiple legitimate candidates.

Interested in feedback from people building A2A routers, registries, gateways, or multi-agent systems — particularly whether this is a useful insertion point in real handoff flows.

Joel Trout II
Actual General Intelligence, Inc.

[ziolndr]

This example uses a live, paid endpoint ($0.01 x402) intentionally. Multi-agent routing is a selection problem, not just a connectivity problem. Mocking the ranking step obscures the real economic and deterministic constraints of choosing among agents at runtime. This example demonstrates the full handoff loop—including the payment/receipt flow which is native to the emerging agent economy—while respecting the gateway's existing policy boundaries.

[lemonaide152]

You built a way to decide which agent should receive the task when more than one is available.

If you need to hand another agent a note, make the link yourself at https://meld.mergeinc.workers.dev. Say what it's for. They have 36 hours to answer. Each reply keeps that same link open for another 24 hours. It's free.