Copilot Studio YAML Reference

Core File Types

File	Purpose
agent.mcs.yml	Main agent metadata (kind: GptComponentMetadata)
settings.mcs.yml	Agent settings and configuration
connectionreferences.mcs.yml	Connector references
topics/*.mcs.yml	Conversation topics (kind: AdaptiveDialog)
actions/*.mcs.yml	Connector-based actions (kind: TaskDialog)
knowledge/*.mcs.yml	Knowledge sources (kind: KnowledgeSourceConfiguration)
variables/*.mcs.yml	Global variables (kind: GlobalVariableComponent)
agents/*.mcs.yml	Child agents (kind: AgentDialog)

Trigger Types

Topics with OnRecognizedIntent have two routing mechanisms — which one matters depends on the orchestration mode:

• modelDescription — used by generative orchestration (GenerativeActionsEnabled: true). The AI orchestrator reads this to decide routing. Primary mechanism for generative agents.
• Trigger phrases (triggerQueries) — used by classic orchestration. Pattern-matched against the user's utterance. Secondary hints when generative orchestration is enabled.

System triggers (OnConversationStart, OnUnknownIntent, OnError, etc.) fire automatically and don't use either mechanism.

Kind	Purpose
OnRecognizedIntent	Trigger phrases matched
OnConversationStart	Conversation begins
OnUnknownIntent	No topic matched (fallback)
OnEscalate	User requests human agent
OnError	Error handling
OnSystemRedirect	Triggered by redirect only
OnSelectIntent	Multiple topics matched (disambiguation)
OnSignIn	Authentication required
OnToolSelected	Child agent invocation
OnKnowledgeRequested	Custom knowledge source search triggered (YAML-only, no UI)
OnGeneratedResponse	Intercept AI-generated response before sending
OnOutgoingMessage	Non-functional (2026-03-15) — exists in schema but does not fire at runtime. Do not use.

YAML-Only Features

These features work at runtime but are not visible in the Copilot Studio UI. Warn users that UI edits may silently remove them.

Feature	Notes
triggerCondition on knowledge sources	The UI only exposes this as an on/off toggle (=false to exclude from UniversalSearchTool). Arbitrary Power Fx expressions (e.g., =Global.UserDepartment = "HR") work at runtime but can only be set via YAML. Use with caution. (2026-03-16)

Action Types

Kind	Purpose
SendActivity	Send a message
Question	Ask user for input
SetVariable	Set/compute a variable (Power Fx expression, prefix =)
SetTextVariable	Set a text variable using template interpolation ({}). Useful for converting non-text types (e.g., Number) to text: "You have {Topic.Count} items"
ConditionGroup	Branching logic
BeginDialog	Call another topic
ReplaceDialog	Replace current topic
EndDialog	End current topic
CancelAllDialogs	Cancel all topics
ClearAllVariables	Clear variables
SearchAndSummarizeContent	Generative answers (grounded in knowledge)
AnswerQuestionWithAI	AI answer (conversation history + general knowledge only)
EditTable	Modify a collection
CSATQuestion	Customer satisfaction
LogCustomTelemetryEvent	Logging
OAuthInput	Sign-in prompt
SearchKnowledgeSources	Search knowledge sources (returns raw results, no AI summary)
CreateSearchQuery	AI-generated search query from user input

Connector Actions (TaskDialog)

Connector actions (kind: TaskDialog) invoke external connector operations. They are stored in actions/ and require a connection reference in connectionreferences.mcs.yml.

Use /add-action to create new actions from available connectors. The schema describes the structural properties of TaskDialog and InvokeConnectorTaskAction, but the specific inputs and outputs for each connector operation are connector-specific — use the connector lookup script (connector-lookup.bundle.js) to get the full operation details.

Action Structure

Field	Purpose
kind: TaskDialog	Identifies this as a connector action
inputs	Inputs: AutomaticTaskInput (AI-provided) or ManualTaskInput (fixed value)
modelDisplayName	Display name for AI orchestrator routing
modelDescription	Description for AI orchestrator routing
outputs	Output property names returned by the connector
action.kind	Always InvokeConnectorTaskAction for connector actions
action.connectionReference	Logical name of the connection (registered in connectionreferences.mcs.yml)
action.connectionProperties.mode	Maker (maker's credentials) or Invoker (end user's credentials)
action.operationId	The connector's specific operation identifier
outputMode	Usually All — exports all operation outputs

Input Types

Input Kind	Use When	Notes
AutomaticTaskInput	The AI orchestrator should provide the value based on context	Includes description for the AI to understand what to provide
ManualTaskInput	A fixed/hardcoded value (e.g., timezone, folder path)	Can only hardcode strings. Non-string values (IDs, enums) should be reviewed by the user after pushing

System Variables

Variable	Description
System.Bot.Name	Agent's name
System.Activity.Text	User's current message
System.Conversation.Id	Conversation identifier
System.Conversation.InTestMode	True if in test chat
System.FallbackCount	Number of consecutive fallbacks
System.Error.Message	Error message
System.Error.Code	Error code
System.SignInReason	Why sign-in was triggered
System.Recognizer.IntentOptions	Matched intents for disambiguation
System.Recognizer.SelectedIntent	User's selected intent
System.SearchQuery	AI-rewritten search query (available in OnKnowledgeRequested)
System.KeywordSearchQuery	Keyword version of search query (available in OnKnowledgeRequested)
System.SearchResults	Table to populate with custom search results — schema: Content, ContentLocation, Title (available in OnKnowledgeRequested)
System.ContinueResponse	Set to false in OnGeneratedResponse to suppress auto-send
System.Response.FormattedText	The AI-generated response text (available in OnGeneratedResponse)

Variable Scopes

Prefix	Scope	Lifetime
Topic.<name>	Topic variable	Current topic only
Global.<name>	Global variable	Entire conversation (defined in variables/ folder)
System.<name>	System variable	Built-in, read-only

Global variables are defined as YAML files in variables/<Name>.mcs.yml (kind: GlobalVariableComponent). aIVisibility accepts UseInAIContext (orchestrator can read and reason about the value) or Hidden (orchestrator unaware — use for flags and internal bookkeeping).

Prebuilt Entities

Entity	Use Case
BooleanPrebuiltEntity	Yes/No questions
NumberPrebuiltEntity	Numeric inputs
StringPrebuiltEntity	Free text
DateTimePrebuiltEntity	Date/time
EMailPrebuiltEntity	Email addresses

Power Fx Expression Reference

Only use functions from the supported list below. Copilot Studio supports a subset of Power Fx — using unsupported functions will cause errors.

# Arithmetic
value: =Text(Topic.number1 + Topic.number2)

# Date formatting
value: =Text(Now(), DateTimeFormat.UTC)

# Conditions
condition: =System.FallbackCount < 3
condition: =Topic.EndConversation = true
condition: =!IsBlank(Topic.Answer)
condition: =System.Conversation.InTestMode = true
condition: =System.SignInReason = SignInReason.SignInRequired
condition: =System.Recognizer.SelectedIntent.TopicId = "NoTopic"

# String interpolation in activity (uses {} without =)
activity: "Error: {System.Error.Message}"
activity: "Error code: {System.Error.Code}, Time (UTC): {Topic.CurrentTime}"

# Record creation
value: "={ DisplayName: Topic.NoneOfTheseDisplayName, TopicId: \"NoTopic\", TriggerId: \"NoTrigger\", Score: 1.0 }"

# Variable initialization (first assignment uses init: prefix)
variable: init:Topic.UserEmail
variable: init:Topic.CurrentTime
# Subsequent assignments omit init:
variable: Topic.UserEmail

Supported Power Fx Functions

These are all the Power Fx functions available in Copilot Studio. Do NOT use any function not on this list.

Math: Abs, Acos, Acot, Asin, Atan, Atan2, Cos, Cot, Degrees, Exp, Int, Ln, Log, Mod, Pi, Power, Radians, Rand, RandBetween, Round, RoundDown, RoundUp, Sin, Sqrt, Sum, Tan, Trunc

Text: Char, Concat, Concatenate, EncodeHTML, EncodeUrl, EndsWith, Find, Left, Len, Lower, Match, MatchAll, Mid, PlainText, Proper, Replace, Right, Search, Split, StartsWith, Substitute, Text, Trim, TrimEnds, UniChar, Upper, Value

Date/Time: Date, DateAdd, DateDiff, DateTime, DateTimeValue, DateValue, Day, EDate, EOMonth, Hour, IsToday, Minute, Month, Now, Second, Time, TimeValue, TimeZoneOffset, Today, Weekday, WeekNum, Year

Logical: And, Coalesce, If, IfError, IsBlank, IsBlankOrError, IsEmpty, IsError, IsMatch, IsNumeric, IsType, Not, Or, Switch

Table: AddColumns, Column, ColumnNames, Count, CountA, CountIf, CountRows, Distinct, DropColumns, Filter, First, FirstN, ForAll, Index, Last, LastN, LookUp, Patch, Refresh, RenameColumns, Sequence, ShowColumns, Shuffle, Sort, SortByColumns, Summarize, Table

Aggregate: Average, Max, Min, StdevP, VarP

Type conversion: AsType, Boolean, Dec2Hex, Decimal, Float, GUID, Hex2Dec, JSON, ParseJSON

Other: Blank, ColorFade, ColorValue, Error, Language, OptionSetInfo, RGBA, Trace, With

Available Templates

Templates are bundled with the plugin. Skills that use templates reference them via ${CLAUDE_SKILL_DIR}/../../templates/.

Template	File	Pattern
Greeting	templates/topics/greeting.topic.mcs.yml	OnConversationStart welcome
Fallback	templates/topics/fallback.topic.mcs.yml	OnUnknownIntent with escalation
Arithmetic	templates/topics/arithmeticsum.topic.mcs.yml	Inputs/outputs with computation
Question + Branching	templates/topics/question-topic.topic.mcs.yml	Question with ConditionGroup
Knowledge Search	templates/topics/search-topic.topic.mcs.yml	SearchAndSummarizeContent fallback
Custom Knowledge Source	templates/topics/custom-knowledge-source.topic.mcs.yml	OnKnowledgeRequested with custom API (YAML-only)
Remove Citations	templates/topics/remove-citations.topic.mcs.yml	OnGeneratedResponse citation stripping
Authentication	templates/topics/auth-topic.topic.mcs.yml	OnSignIn with OAuthInput
Error Handler	templates/topics/error-handler.topic.mcs.yml	OnError with telemetry
Disambiguation	templates/topics/disambiguation.topic.mcs.yml	OnSelectIntent flow
Agent	templates/agents/agent.mcs.yml	GptComponentMetadata
Connector Action (generic)	templates/actions/connector-action.mcs.yml	TaskDialog with connector (structural reference)
Knowledge (Public Website)	templates/knowledge/public-website.knowledge.mcs.yml	PublicSiteSearchSource
Knowledge (SharePoint)	templates/knowledge/sharepoint.knowledge.mcs.yml	SharePointSearchSource
Global Variable	templates/variables/global-variable.variable.mcs.yml	GlobalVariableComponent