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A Big Number is a single-value KPI chart, which is useful for showing a total, the latest reading, or an aggregated metric at a glance (e.g. total errors, current queue depth, mean request latency). This page covers how to use that feature from an AI agent connected to AppSignal MCP. For a tour of all dashboard chart types in the UI, see Dashboards.

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What you can do

With the dashboards permission set to write, an agent can:
  • Create a new dashboard to hold the chart (manage_dashboard)
  • Add a Big Number chart to any dashboard (create_dashboard_visual with type: "number")
  • Change the metric, aggregate, or formatting on an existing chart (update_dashboard_visual)
The chart renders the same way as one built in the AppSignal app, MCP is just another way to author it. Big Number chart on a dashboard

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Example prompt

Text
Add a Big Number chart to the "API Health" dashboard showing the mean
of request_latency_ms over the selected time range, formatted as a duration.
The agent will translate that into a create_dashboard_visual call with:
  • type: "number"
  • metric.name: "request_latency_ms"
  • metric.field: "mean"
  • metric.aggregate: "avg"
  • format: "duration"

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Configuring the chart

A Big Number chart needs one metric and one aggregation across the selected time range:
  • Metric — The metric name to be shown in this chart. You can either use the full metric name to select one metric, or use a wildcard (_) to select multiple metrics at once: db_users_document_count, db\__\_size. See metric naming for the full rules.
  • Aggregation type — The aggregation used to display the metric value. The number on the chart is selected or calculated based on this aggregation, applied to the metric data reported in the selected time frame on the dashboard or preview:
    • Maximum value — the highest metric value
    • Minimum value — the lowest metric value
    • Average value — the average of the metric values
    • Total value — the combined value of the metric values
    • First value — the first metric value
    • Last value — the last metric value
  • Data format — Select the value format that is used to display values in the chart and chart legends. See value formatting for the available formats.
  • Tags (optional) — Select which tags of the metric should be displayed in the chart:
    • When empty, all variations of a tag will create their own line in the chart.
    • Enter tags to filter for certain tag values. In this case, all tags of the metric need to be specified, either with a value or a wildcard.
    See metric tags for the full reference.
Big Number chart setup in the AppSignal UI

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Sending the data

MCP authors the visual; it does not ingest metrics. The metric you point a chart at must already be flowing into AppSignal via your integration. See custom metrics for how to send them from your application.