Tool Reference

Complete reference for all UEBPCracker MCP tools. All tools are dispatched through call_tool with the nested arguments format.

MCP call structure:

{
  "params": {
    "name": "call_tool",
    "arguments": {
      "toolset_name": "UEBPCrackerEditor.UEBPCrackerToolset",
      "tool_name": "ToolNameHere",
      "arguments": { ... }
    }
  }
}

Tool names are PascalCase — HealthCheck, not health_check.

Read-Only Tools (L0)

`HealthCheck`

Returns plugin version, engine version, write roots, and policy fingerprint.

Parameters: none

Response:

{
  "success": true,
  "engineVersion": "5.8.2",
  "pluginVersion": "0.1.0",
  "toolsetVersion": "0.1.0",
  "writeRoots": ["/Game/AI/"],
  "bWriteEnabled": true,
  "bLoopbackBind": true,
  "policyFingerprint": "sha1:5308baef..."
}

`GetCapabilities`

Returns full capability summary: tools, resource limits, security policy, domain availability.

Parameters: none

Response includes:

tools[] — all registered tool names
resourceLimits — hard ceilings (nodes, connections, snapshot size, etc.)
securityPolicy — L0–L3 gates, write roots, plan hash requirement
domains[] — Extra module domain status

`InspectBlueprint`

Full Blueprint dump: variables, components, graphs, nodes, pins, connections, fingerprint.

Parameters:

Parameter	Type	Required	Description
`blueprint_path`	string	✅	Content path e.g. `/Game/AI/BP_HealthActor`
`include_nodes`	bool	No	Include node list per graph (default: true)
`include_pins`	bool	No	Include pin details per node (default: true)
`include_connections`	bool	No	Include connection list (default: true)
`include_fingerprint`	bool	No	Include semantic/layout/full fingerprints (default: true)

Response excerpt:

{
  "success": true,
  "assetPath": "/Game/AI/BP_HealthActor",
  "parentClass": "/Script/Engine.Actor",
  "variables": [
    { "name": "Health", "type": "float", "defaultValue": "100.0", "instanceEditable": true }
  ],
  "components": [
    { "name": "DefaultSceneRoot", "class": "SceneComponent", "isRoot": true }
  ],
  "graphs": [
    {
      "name": "EventGraph",
      "kind": "event_graph",
      "nodes": [ ... ],
      "connections": [ ... ]
    }
  ],
  "fingerprint": {
    "semantic": "blake3:f820f1d1...",
    "layout": "blake3:a3c4e5f6...",
    "full": "blake3:9b2c1d8e..."
  }
}

`InspectBlueprintGraph`

Detailed inspection of a single graph.

Parameters:

Parameter	Type	Required	Description
`blueprint_path`	string	✅	Blueprint content path
`graph_name`	string	✅	Graph name e.g. `EventGraph`, `OnCalculateDamage`

`ResolveUnrealType`

Resolves a type string to its canonical Unreal representation.

Parameters:

Parameter	Type	Required	Description
`type_name`	string	✅	Type name e.g. `float`, `FVector`, `AActor`, `/Script/Engine.Actor`

Response:

{
  "success": true,
  "canonical": "float",
  "category": "real",
  "subCategory": "float",
  "containerType": "None",
  "isValid": true
}

`GetBlueprintSnapshot`

Creates a named snapshot with Blake3 fingerprints and stores it in the 32-slot FIFO.

Parameters:

Parameter	Type	Required	Description
`blueprint_path`	string	✅	Blueprint content path
`include_layout`	bool	No	Include layout fingerprint and node positions (default: false)

Response:

{
  "success": true,
  "snapshotId": "snapshot:a3b4c5d6-...",
  "semanticFingerprint": "blake3:f820f1d1...",
  "layoutFingerprint": "blake3:a3c4e5f6...",
  "fullFingerprint": "blake3:9b2c1d8e..."
}

Snapshot IDs are stable across editor restarts. Fingerprints are restart-stable (verified at 59/59 assertions).

`CompareBlueprintSnapshots`

Element-level diff between two snapshots.

Parameters:

Parameter	Type	Required	Description
`snapshot_id_a`	string	✅	First snapshot ID (e.g. `snapshot:...`)
`snapshot_id_b`	string	✅	Second snapshot ID

Response: diff entries with logical paths (e.g. variables/Health/defaultValue), before/after values, change type.

`GetRecoveryStatus`

Lists pending recovery operations (from interrupted apply/patch).

Parameters: none

`CheckCompletion`

Evaluates the 31-criterion DoD (code c01–c08, behavior b01–b08, security s01–s07, test_release t01–t08).

Parameters: none

Write Tools (L1 — requires `bEnableWriteOperations=True`)

`CreateBlueprint`

Creates a new Actor-based Blueprint asset.

Parameters:

Parameter	Type	Required	Description
`request_id`	string	✅	Client-provided idempotency key
`asset_path`	string	✅	Full content path e.g. `/Game/AI/BP_HealthActor`
`parent_class`	string	✅	Class path e.g. `/Script/Engine.Actor`
`conflict_policy`	enum	No	`reject` (default) · `overwrite` · `rename`
`dry_run`	bool	No	If true, validates and returns plan without mutating

Response:

{
  "success": true,
  "requestId": "req-001",
  "operation": "create_blueprint",
  "assetPath": "/Game/AI/BP_HealthActor",
  "stage": "save",
  "compileStatus": "success",
  "errors": [],
  "warnings": [],
  "saved": true,
  "transactionId": "txn:...",
  "fingerprint": { "semantic": "blake3:..." }
}

`AddVariable`

Adds a typed variable to an existing Blueprint.

Parameters:

Parameter	Type	Required	Description
`request_id`	string	✅
`blueprint_path`	string	✅
`variable_name`	string	✅
`variable_type`	string	✅	`float`, `int32`, `bool`, `FString`, `FVector`, `/Script/Engine.Actor` (object ref), etc.
`default_value`	string	No	JSON-encoded default (codec round-trip validated)
`instance_editable`	bool	No
`expose_on_spawn`	bool	No
`replication`	string	No	`None`, `Replicated`, `RepNotify`
`category`	string	No
`dry_run`	bool	No

Type examples:

"float"           → simple float
"TArray<float>"   → float array
"TMap<FString,int32>" → map
"/Script/Engine.StaticMeshComponent" → soft object ref

`AddComponent`

Adds an SCS component to the Blueprint's Simple Construction Script.

Parameters:

Parameter	Type	Required	Description
`request_id`	string	✅
`blueprint_path`	string	✅
`component_name`	string	✅
`component_class`	string	✅	Class path e.g. `/Script/Engine.StaticMeshComponent`
`parent_component`	string	No	Parent component name (defaults to root)
`dry_run`	bool	No

`AddFunctionGraph`

Adds a new named function graph to the Blueprint.

Parameters:

Parameter	Type	Required	Description
`request_id`	string	✅
`blueprint_path`	string	✅
`graph_name`	string	✅	Must not collide with existing graphs (ScriptName meta checked)
`dry_run`	bool	No

Note: AddFunctionGraph creates ONLY the entry node. Use AddNode to add a result/return node if needed.

`AddNode`

Adds a K2 node to a graph. Nine allow-listed node kinds.

Parameters:

Parameter	Type	Required	Description
`request_id`	string	✅
`blueprint_path`	string	✅
`graph_name`	string	✅
`node_kind`	enum	✅	See below
`node_id`	string	✅	Spec-local logical ID
`position_x`	int	No	Grid X (snapped to 16-unit floor by engine)
`position_y`	int	No	Grid Y
`dry_run`	bool	No

Node kinds and their extra parameters:

Kind	Extra Parameters	Notes
`event_override`	`event_name` (e.g. `ReceiveBeginPlay`), `event_owner_class`	Use `ReceiveBeginPlay` not `BeginPlay` (AActor::BeginPlay is not UFUNCTION)
`function_call`	`function_path` (`/Script/Engine.KismetSystemLibrary:PrintString`)	Spawned via `UBlueprintFunctionNodeSpawner`
`variable_get`	`variable_name`
`variable_set`	`variable_name`
`branch`	—	If/else flow control
`sequence`	`output_count`
`cast`	`cast_target_class`
`comment`	`comment_text`, `width`, `height`	`UEdGraphNode_Comment`
`macro_instance`	`macro_path`

Position snapping: Engine snaps to 16 * floor(V/16). Position 1000 → 992, 600 → 592. Postcondition accepts both requested and snapped coordinates.

`SetPinDefault`

Sets a pin's default value (for unconnected input pins).

Parameters:

Parameter	Type	Required	Description
`request_id`	string	✅
`blueprint_path`	string	✅
`graph_name`	string	✅
`node_id`	string	✅	Logical node ID or Unreal node GUID
`pin_name`	string	✅	Internal pin name (NOT the display label)
`default_value`	string	✅	Raw value string (codec round-trip validated)
`dry_run`	bool	No

Uses UEdGraphSchema_K2::TrySetDefaultValue. Invalid values are caught by IsPinDefaultValid and rejected with INVALID_PIN_DEFAULT.

`ConnectPins`

Creates a pin connection between two nodes.

Parameters:

Parameter	Type	Required	Description
`request_id`	string	✅
`blueprint_path`	string	✅
`graph_name`	string	✅
`from_node_id`	string	✅	Source node logical ID or GUID
`from_pin_name`	string	✅	Source pin internal name
`to_node_id`	string	✅	Target node logical ID or GUID
`to_pin_name`	string	✅	Target pin internal name
`dry_run`	bool	No

Connection policy responses:

Schema response	Plugin action
`MAKE`	Connection created
`BREAK_OTHERS_AND_MAKE`	Existing connections broken, new one made
`MAKE_WITH_CONVERSION_NODE`	Requires conversion — rejected (`REQUIRES_CONVERSION`)
Anything else	Rejected (`INCOMPATIBLE_PINS`)

Spec Tools

`ValidateBlueprintSpec`

Validates a .uebp.json file (schema + semantic) and returns the execution plan without mutating anything.

Parameters:

Parameter	Type	Required	Description
`file`	string	✅	Relative path from spec root (e.g. `BP_HealthActor.uebp.json`)

`PlanBlueprintSpec`

Same as ValidateBlueprintSpec but also returns the full deterministic command list.

Parameters: same as ValidateBlueprintSpec

`ApplyBlueprintSpec`

Validates, plans, and executes a .uebp.json spec in a single transaction.

Parameters:

Parameter	Type	Required	Description
`file`	string	✅	Relative spec path
`dry_run`	bool	No	If true, returns plan without executing
`expected_plan_hash`	string	No	Sealed plan hash for integrity verification

Patch Tools (L2 — requires `bRequirePlanHashForPatch=True`)

`PlanBlueprintPatch`

Three-way ownership diff (base snapshot vs. current Blueprint vs. incoming spec). Returns a sealed plan hash.

Parameters:

Parameter	Type	Required	Description
`file`	string	✅	Spec file path
`blueprint_path`	string	✅	Target Blueprint

Response includes: planHash, commands[], conflict report, noOpCount, patchCount, conflictCount

`ApplyBlueprintPatch`

Applies a previously planned patch using the sealed hash for integrity.

Parameters:

Parameter	Type	Required	Description
`file`	string	✅
`blueprint_path`	string	✅
`expected_plan_hash`	string	✅	Must match; `PLAN_HASH_MISMATCH` if not
`dry_run`	bool	No

Recovery Tools (L3 — requires `bEnableDestructiveOperations=True`)

`RestoreOperationBackup`

Restores a Blueprint from a durable backup asset created during a failed apply/patch.

Parameters:

Parameter	Type	Required	Description
`operation_id`	string	✅	Recovery operation ID from `GetRecoveryStatus`
`expected_content_fingerprint`	string	No	Verify content fingerprint after restore

`DiscardOperationBackup`

Permanently deletes a backup asset (use after manual resolution).

Parameters:

Parameter	Type	Required	Description
`operation_id`	string	✅

⚠️ This is irreversible. After discard, RestoreOperationBackup returns BACKUP_INVALID.

Domain Tools (Extra Modules)

`GetDomainCapabilities`

Returns the availability and operation status of each domain adapter.

Parameters:

Parameter	Type	Required	Description
`domain`	string	No	Specific domain ID (`ai`, `data`, `fx`, `gameplay`, `input`, `project`, `ui`) or `all`

Response:

{
  "domains": [
    { "id": "input", "available": true, "ops": ["create_action", "inspect_action", "create_mapping_context", ...] },
    { "id": "ai", "available": false, "ops": [] }
  ]
}

Tool Reference

Tool Reference

Read-Only Tools (L0)

HealthCheck

GetCapabilities

InspectBlueprint

InspectBlueprintGraph

ResolveUnrealType

GetBlueprintSnapshot

CompareBlueprintSnapshots

GetRecoveryStatus

CheckCompletion

Write Tools (L1 — requires bEnableWriteOperations=True)

CreateBlueprint

AddVariable

AddComponent

AddFunctionGraph

AddNode

SetPinDefault

ConnectPins

Spec Tools

ValidateBlueprintSpec

PlanBlueprintSpec

ApplyBlueprintSpec

Patch Tools (L2 — requires bRequirePlanHashForPatch=True)

PlanBlueprintPatch

ApplyBlueprintPatch

Recovery Tools (L3 — requires bEnableDestructiveOperations=True)

RestoreOperationBackup

DiscardOperationBackup

Domain Tools (Extra Modules)

GetDomainCapabilities

See Also

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Clone this wiki locally

`HealthCheck`

`GetCapabilities`

`InspectBlueprint`

`InspectBlueprintGraph`

`ResolveUnrealType`

`GetBlueprintSnapshot`

`CompareBlueprintSnapshots`

`GetRecoveryStatus`

`CheckCompletion`

Write Tools (L1 — requires `bEnableWriteOperations=True`)

`CreateBlueprint`

`AddVariable`

`AddComponent`

`AddFunctionGraph`

`AddNode`

`SetPinDefault`

`ConnectPins`

`ValidateBlueprintSpec`

`PlanBlueprintSpec`

`ApplyBlueprintSpec`

Patch Tools (L2 — requires `bRequirePlanHashForPatch=True`)

`PlanBlueprintPatch`

`ApplyBlueprintPatch`

Recovery Tools (L3 — requires `bEnableDestructiveOperations=True`)

`RestoreOperationBackup`

`DiscardOperationBackup`

`GetDomainCapabilities`