Declaring Discovery Metadata - StellarX402

The describe block is how your endpoint appears in the Bazaar. It is not optional if you want to be found, and it is not a place to over-market — agents filter on capability, not adjectives.

The full shape

requirePayment({
  ...,
  describe: {
    title: "5-day weather forecast",
    description: "Returns hourly weather forecast for the next 5 days given a lat/lng.",
    tags: ["weather", "forecast", "noaa"],
    inputs: {
      lat: { type: "number", description: "Latitude, WGS-84" },
      lng: { type: "number", description: "Longitude, WGS-84" },
    },
    outputs: {
      type: "object",
      properties: {
        hourly: { type: "array", items: { type: "object" } },
      },
    },
    template: "/weather/{lat}/{lng}", // optional: overrides route inference
  },
});

Field-by-field

Field	Required	Notes
`title`	yes	Short, one line. Weighted heavily in search.
`description`	yes	One paragraph. Explain what, not how.
`tags`	recommended	Filterable facets. Use nouns, not adjectives.
`inputs`	recommended	Machine-readable input schema. Agents match this to their available context.
`outputs`	recommended	JSON Schema of the response shape.
`template`	optional	Override route inference for dynamic paths. See Route Template & Integrity.

Writing a description agents can use

Do:

State the input and the output in one sentence.
Name the domain (“weather,” “exchange rates,” “OCR”) explicitly — agents search on it.
Include constraints that would surprise an agent (“5-day horizon,” “US only,” “cached hourly”).

Do not:

Advertise (“the best weather API in the world”). Ranking discounts marketing language.
Rely on brand names agents will not know.
Repeat the title.