Rich output

An agent can attach structured visuals (tables, metrics, charts, cards) to its answer with the present tool. The components follow AstralPrimitives, the component schema Astral's clients render.

AstralPrimitives

AstralPrimitives (the astralprims package) is by the AstralDeep project and licensed under Apache 2.0. AstralVessel uses it, when installed, to validate components.

Turn it on

[output]
primitives = true

The agent gets a present tool (scope tools:read), and its system prompt asks it to call present once before its final message and still write the complete answer in Markdown. Components add to the answer; they never replace it.

What the model sends

present takes one argument, components, a list in display order:

{"components": [
  {"type": "metric", "title": "Species", "value": "4"},
  {"type": "table", "title": "Lengths", "headers": ["Name", "cm"], "rows": [["Great Blue Heron", 115]]},
  {"type": "bar_chart", "title": "Length by species", "labels": ["Heron", "Hawk"],
   "datasets": [{"label": "cm", "data": [115, 56]}]}
]}

The tool description lists these shapes for the model: metric, stat_group, table, bar_chart, line_chart, key_value, list, card, alert and text.

At most 12 components and 200,000 bytes of JSON per answer (see Limits). A later present call in the same turn replaces the earlier components.

Validation

astralprims installed	Check
Yes	Each component is validated and normalized by AstralPrimitives. The AstralVessel image installs astralprims==0.12.0.
No	Each component must be an object whose type is one of metric, stat_group, table, bar_chart, line_chart, pie_chart, key_value, list, card, alert, text, badge, divider, container, grid, timeline.

An invalid list is refused with the first problem, and the model is asked to fix it and call present again.

To validate outside the image, for example in tests, install the optional extra:

pip install "astralvessel[primitives]"     # astralprims>=0.12,<1; from a checkout: pip install -e ".[primitives]"

Where components appear

The answer artifact carries the Markdown text part and, when components were attached, a second part:

{
  "mediaType": "application/vnd.astral.primitives+json",
  "data": {"_ui_components": [{"type": "metric", "title": "Species", "value": "4"}]},
  "metadata": {"schema_version": "0.12.0"}
}

schema_version is the installed astralprims version, or unvalidated without it. Astral renders components from _ui_components. The agent card adds application/vnd.astral.primitives+json to its defaultOutputModes, and the Python client returns them as the answer event's components.