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shinymcp use cases

Source: vignettes/use-cases.Rmd
use-cases.Rmd

shinymcp is strongest when an AI assistant needs to do more than print a number. The assistant can call a tool, receive structured data for reasoning, and show the user an interactive card with controls, tables, plots, and formatted output.

The package includes a use-case gallery with three small but realistic MCP Apps:

Use case What it demonstrates
Revenue scenario board Scenario controls, model-facing structured values, a table, and an ARR plot
Experiment planner Statistical planning, a power curve, and a concise recommendation
Incident triage console Operational decision support, status HTML, and a runbook table

The apps are intentionally card-sized: controls fit in a compact grid, the primary answer is immediately visible, and secondary tables stay available without taking over the chat transcript.

Run a use case as an MCP App

The gallery entrypoint serves one use case at a time. Set SHINYMCP_USE_CASE to revenue, experiment, or incident.

SHINYMCP_USE_CASE=revenue Rscript \
  "$(Rscript -e 'cat(system.file("examples", "use-cases", "app.R", package = "shinymcp"))')"

For Claude Desktop or another MCP host, point the server command at that same app.R file and set the environment variable for the use case you want to show.

Revenue scenario board

This card turns go-to-market assumptions into a twelve-month forecast. The assistant can reason over the structured result while the user sees the ARR trajectory and monthly forecast table.

source(system.file("examples", "use-cases", "apps.R", package = "shinymcp"))
app <- shinymcp_use_case("revenue")
app$call_tool("forecast_revenue", list(
  segment = "Mid-market",
  visitors = 25000,
  trial_rate = 7,
  win_rate = 22,
  contract_value = 9000,
  monthly_churn = 2.5
))

Experiment planner

This card helps an assistant move from “can we detect a 15% lift?” to a specific sample size and runtime. The plot gives the human reviewer a quick sense of how much margin the design has.

source(system.file("examples", "use-cases", "apps.R", package = "shinymcp"))
app <- shinymcp_use_case("experiment")
app$call_tool("plan_experiment", list(
  baseline_rate = 12,
  minimum_effect = 15,
  target_power = 0.9,
  traffic_per_day = 6000
))

Incident triage console

This card is useful for support, SRE, and operations chats. The assistant can collect facts conversationally, call the tool, and return a priority, briefing, and runbook without losing the structured values it needs for follow-up.

source(system.file("examples", "use-cases", "apps.R", package = "shinymcp"))
app <- shinymcp_use_case("incident")
app$call_tool("triage_incident", list(
  service = "Payments",
  severity = "Degraded",
  affected_users = 1200,
  minutes_open = 24,
  regulated_data = TRUE
))

shinychat integration

The gallery also includes a Shiny app that registers all three cards as shinychat tool results through as_shinychat_tool().

Rscript "$(Rscript -e 'cat(system.file("examples", "use-cases", "shinychat-app.R", package = "shinymcp"))')"

When OPENAI_API_KEY is available, that app uses chat_mod_ui() and chat_mod_server() with one ellmer client per Shiny session. Without a configured model provider, it falls back to local demo mode: type revenue, experiment, or incident and the app appends a live shinymcp card directly.

The Shiny session is still the runtime for those cards: it registers the McpApp, receives bridge events from the iframe, and executes tool calls in R. The iframe itself remains a portable MCP App surface instead of a nested Shiny app, which keeps each chat card small and reusable outside Shiny.

Why these examples matter

These examples cover the surfaces most teams need before adopting MCP Apps:

  • Rich UI for people: inputs, tables, plots, and formatted HTML.
  • Structured values for the model: the assistant can reason over numbers without scraping the display.
  • Portable deployment: the same McpApp can be served to an MCP host, embedded in Shiny, or wrapped as a shinychat tool card.
  • Small cards over giant dashboards: each card has one job and maps cleanly to one tool call.