Choose what the model sees of a Shiny app

In a Shiny app served with as_mcp_app(), every input becomes an argument of the app's tool and every output is reported to the model. Mark some of them with bindMcp() and only the marked ones are: the model gets a smaller tool that is easier to use well. The person using the app still sees all of it.

ui <- fluidPage(
  selectInput("species", "Species", species) |> bindMcp(),
  sliderInput("alpha", "Point opacity", 0, 1, 0.7),
  plotOutput("scatter") |> bindMcp(),
  verbatimTextOutput("debug")
)

Here the model can set the species and reads the plot; the opacity slider and the debug output stay between the app and its user. Action buttons are only pressed by the model when marked.

In a UI for mcp_app(), bindMcp() marks an element as an input or an output of the app's tools when shinymcp can't tell on its own.

bindMcp() recognizes Shiny's and bslib's inputs and outputs, and htmlwidget outputs. For anything else, give type. Marking an element twice does nothing.

Usage

bindMcp(tag, ...)

# S3 method for class 'shiny.tag'
bindMcp(tag, id = NULL, type = NULL, ...)

# S3 method for class 'shiny.tag.list'
bindMcp(tag, id = NULL, type = NULL, ...)

# Default S3 method
bindMcp(tag, ...)

Arguments

tag

A tag or tag list from a Shiny input or output function.

...

Unused.

id

The id to use, when it isn't the element's own.

type

For outputs: "text", "html", "plot", "table", "image", or "widget". Usually detected; required to mark an element shinymcp doesn't recognize.

Value

tag, marked.

Shiny's own MCP support

Shiny is gaining MCP support of its own (https://github.com/rstudio/shiny/pull/4407). Once it is released, it will be the way to put a live Shiny app in a chat, and shinymcp will stop serving live apps. as_mcp_app(), mcp_endpoint(), and mcp_tool_module() will take only apps built from tools, and bindMcp() and the helpers for server functions (mcp_model_context(), mcp_host_context(), and the rest) will be removed. For something the model should be able to use on its own, rewrite that part of the app as tools with mcp_app(); see vignette("rewriting-as-tools").

See also

Other apps: McpApp, as_mcp_app(), mcp_app(), mcp_tool_module()

Examples

shiny::selectInput("species", "Species", c("Adelie", "Gentoo")) |>
  bindMcp()
#> <div class="form-group shiny-input-container">
#>   <label class="control-label" id="species-label" for="species">Species</label>
#>   <div>
#>     <select id="species" class="shiny-input-select" data-shinymcp-input="species"><option value="Adelie" selected>Adelie</option>
#> <option value="Gentoo">Gentoo</option></select>
#>     <script type="application/json" data-for="species" data-nonempty="">{"plugins":["selectize-plugin-a11y"]}</script>
#>   </div>
#> </div>