| name | a2a |
| description | Agent-to-Agent protocol bridge for Ouroboros. Provides a local A2A-compatible server plus client tools for discovering and messaging other A2A agents. |
| version | 1.3.0 |
| type | extension |
| entry | plugin.py |
| runtime | python3 |
| permissions | ["net","tool","route","widget","companion_process","inject_chat"] |
| env_from_settings | [] |
| when_to_use | User asks to communicate with another A2A-compatible agent, discover an agent card, send an A2A message, check A2A task status, or expose this Ouroboros instance as an A2A peer. |
| timeout_sec | 120 |
| install_specs | [{"kind":"pip","package":"protobuf<6"},{"kind":"pip","package":"a2a-sdk[http-server]>=1.0.0,<2.0.0"}] |
| companion_processes | [{"name":"a2a_server","command":["python3","scripts/a2a_daemon.py"],"runtime":"python3","restart_policy":"on_failure"}] |
A2A skill
Note for reviewers: the companion daemon is declared in this manifest's
frontmatter under companion_processes (name a2a_server, argv
[python3, scripts/a2a_daemon.py], runtime python3, restart policy
on_failure) and is registered at load via
api.register_companion_process("a2a_server"). The host's extension
loader resolves the descriptor from the frontmatter; review-prompt
manifest summaries may omit the companion_processes field, so consult
the frontmatter above for the authoritative declaration.
This skill moves Ouroboros's Agent-to-Agent protocol support out of the
core runtime. It exposes a small local A2A-compatible JSON-RPC server and
registers three client tools:
discover — fetch another agent's Agent Card.send — send a message to another A2A agent.status — check a remote task status.
The companion process talks back to the host through the loopback Host
Service API using the reviewed SkillToken grant. It does not patch the
core runtime and stores task state under the skill state directory.
Outbound peer credentials
The client tools (discover, send, status) send HTTP Basic credentials only
to ONE explicitly configured peer. Set both A2A_CLIENT_PASSWORD and
A2A_CLIENT_PEER_URL; the credential is attached only when the target URL's
origin (scheme, host, port) exactly matches that configured origin, and every
other peer is contacted anonymously. This is deliberate: the tools accept an
arbitrary caller-supplied URL, so a process-wide credential would be handed to
whatever address the model happened to pass.
Agent card
The published Agent Card describes what this Ouroboros instance actually
does, capability-first. The top-level name is the stable product name
Ouroboros (operator-set A2A_AGENT_NAME wins when configured — the host
/identity name is deliberately NOT used: it is the identity document's
first heading, a section title like "Who I Am", not an agent name). The
description leads with a curated capability summary and appends the host
/identity first line as flavor (A2A_AGENT_DESCRIPTION overrides the
whole field). The skill list always begins with five curated capability
categories (code and files, web and media, long-running tasks and
projects, self-modification, skills), followed by live per-tool entries
from the host tool schemas (). A discovery GET answers
in seconds: the request path uses the last known-good tool list and a
short fetch only, while a background refresher owns the long host-warmup
retry ladder and keeps the list warm. When the tool registry is genuinely
unavailable the card still carries the curated categories — it never
collapses to a contentless "General" stub nor to an identity-persona-only
entry.
