user-invocable: false description: Add a global variable to a Copilot Studio agent. Use when the user needs a variable that persists across topics in the same conversation and can optionally be visible to the AI orchestrator. argument-hint: <variable name and purpose> allowed-tools: Read, Write, Glob, Grep context: fork agent: copilot-studio-author

Add Global Variable

Create a global variable that persists across all topics within a conversation.

Instructions

1. Auto-discover the agent directory:

   Glob: **/agent.mcs.yml
   

   Use the top-level agent. NEVER hardcode an agent name.

2. Read settings.mcs.yml to get the schemaName prefix:

   Read: <agent-dir>/settings.mcs.yml
   

   Extract the root-level schemaName value (e.g., copilots_header_cre3c_fullagent).

3. Determine from the user:

   • Variable name (PascalCase, e.g., LastDiscussedCity)
   • Description of what it stores
   • Whether the AI orchestrator should be aware of it (aIVisibility)
   • Default value (if any)
   • DO NOT skip any of these properties. If the user doesn't provide them, ask follow-up questions to get the necessary information.

4. Create the variable file at <agent-dir>/variables/<VariableName>.mcs.yml:

# Name: <Human-readable Name>
# <Description>
name: <VariableName>
aIVisibility: <UseInAIContext or HideFromAIContext>
scope: Conversation
description: <Description of what the variable stores>
schemaName: <prefix>.globalvariable.<VariableName>
kind: GlobalVariableComponent
defaultValue: <DEFAULT or specific value>

1. Key fields explained:
   • name — PascalCase identifier. This is how topics reference the variable: Global.<name> (e.g., Global.LastDiscussedCity).
   • aIVisibility — Controls orchestrator awareness:
     • UseInAIContext — The orchestrator can read and reason about this variable. Use when the variable influences routing or response generation (e.g., user preferences, conversation state the AI should track).
     • HideFromAIContext — The variable exists but the orchestrator doesn't see it. Use for internal bookkeeping (e.g., counters, flags) that topics use but the AI doesn't need to reason about.
   • scope: Conversation — Always Conversation for global variables (persists for the session).
   • schemaName — Must follow the pattern <agent-schemaName>.globalvariable.<VariableName>. Read the prefix from settings.mcs.yml.
   • defaultValue — Initial value. Use DEFAULT if no specific initial value is needed.

How Topics Use Global Variables

Topics reference global variables with the Global. prefix:

# Reading a global variable in a condition
- kind: ConditionGroup
  id: conditionGroup_Xk9mPq
  conditions:
    - id: conditionItem_Lw3nRs
      condition: =!IsBlank(Global.LastDiscussedCity)
      actions:
        - kind: SendActivity
          id: sendMessage_Yt7vBw
          activity:
            text:
              - "Last time we discussed {Global.LastDiscussedCity}."

# Setting a global variable from a topic
- kind: SetTextVariable
  id: setTextVariable_Qp4kMn
  variable: Global.LastDiscussedCity
  value: =Topic.CityName

When to Use Global Variables

• Cross-topic state: A value set in one topic needs to be read in another (e.g., user's preferred language, last search query)
• AI-aware context: The orchestrator should know something about the conversation state to make better routing decisions (use UseInAIContext)
• Conversation-wide defaults: A default value that multiple topics can read and optionally override
• Dynamic knowledge sources: A global variable can hold a URL that a knowledge source references via =$"{Global.VarName}". This enables routing to different SharePoint folders or websites per user (e.g., by geolocation or department). See /copilot-studio:add-knowledge for the full pattern. Important: the variable value must be a clean, direct URL — not a SharePoint AllItems.aspx link with query parameters.