Add support for additional context properties

CHANGELOG.md

@@ -25,6 +25,8 @@ changes accumulate. Track in-flight protocol changes via PRs touching
 
 ### Added
 
+- `SessionModelInfo.maxOutputTokens` and `SessionModelInfo.maxPromptTokens`
+  optional fields for communicating model token limits.
 - `SessionSummary._meta` optional provider metadata field for lightweight
   session-list presentation hints.
 

clients/go/CHANGELOG.md

@@ -16,6 +16,8 @@ tag whose matching `## [X.Y.Z]` heading is missing from this file.
 
 ### Added
 
+- `SessionModelInfo.MaxOutputTokens` and `SessionModelInfo.MaxPromptTokens`
+  optional fields for communicating model token limits.
 - `SessionSummary.Meta` (wire `_meta`) optional provider metadata field for
   lightweight session-list presentation hints.
 

clients/go/ahptypes/state.generated.go

@@ -539,6 +539,10 @@ type SessionModelInfo struct {
 	Name string `json:"name"`
 	// Maximum context window size
 	MaxContextWindow *int64 `json:"maxContextWindow,omitempty"`
+	// Maximum number of output tokens the model can generate
+	MaxOutputTokens *int64 `json:"maxOutputTokens,omitempty"`
+	// Maximum number of prompt (input) tokens the model accepts
+	MaxPromptTokens *int64 `json:"maxPromptTokens,omitempty"`
 	// Whether the model supports vision
 	SupportsVision *bool `json:"supportsVision,omitempty"`
 	// Policy configuration state

clients/kotlin/CHANGELOG.md

@@ -17,6 +17,8 @@ versions (`*-SNAPSHOT`) are explicitly rejected by the publish pipeline; bump
 
 ### Added
 
+- `SessionModelInfo.maxOutputTokens` and `SessionModelInfo.maxPromptTokens`
+  optional fields for communicating model token limits.
 - `SessionSummary.meta` (`_meta` on the wire) optional provider metadata field
   for lightweight session-list presentation hints.
 

clients/kotlin/src/main/kotlin/com/microsoft/agenthostprotocol/generated/State.generated.kt

@@ -894,6 +894,14 @@ data class SessionModelInfo(
      * Maximum context window size
      */
     val maxContextWindow: Long? = null,
+    /**
+     * Maximum number of output tokens the model can generate
+     */
+    val maxOutputTokens: Long? = null,
+    /**
+     * Maximum number of prompt (input) tokens the model accepts
+     */
+    val maxPromptTokens: Long? = null,
     /**
      * Whether the model supports vision
      */

clients/rust/CHANGELOG.md

@@ -17,6 +17,8 @@ matching `## [X.Y.Z]` heading is missing from this file.
 
 ### Added
 
+- `SessionModelInfo.maxOutputTokens` and `SessionModelInfo.maxPromptTokens`
+  optional fields for communicating model token limits.
 - `SessionSummary.meta` (`_meta` on the wire) optional provider metadata field
   for lightweight session-list presentation hints.
 - `ahp-ws` TLS backend is now selectable via Cargo features: `native-tls`,

clients/rust/crates/ahp-types/src/state.rs

@@ -750,6 +750,12 @@ pub struct SessionModelInfo {
     /// Maximum context window size
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub max_context_window: Option<i64>,
+    /// Maximum number of output tokens the model can generate
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub max_output_tokens: Option<i64>,
+    /// Maximum number of prompt (input) tokens the model accepts
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub max_prompt_tokens: Option<i64>,
     /// Whether the model supports vision
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub supports_vision: Option<bool>,

clients/swift/AgentHostProtocol/Sources/AgentHostProtocol/Generated/State.generated.swift

@@ -596,6 +596,10 @@ public struct SessionModelInfo: Codable, Sendable {
     public var name: String
     /// Maximum context window size
     public var maxContextWindow: Int?
+    /// Maximum number of output tokens the model can generate
+    public var maxOutputTokens: Int?
+    /// Maximum number of prompt (input) tokens the model accepts
+    public var maxPromptTokens: Int?
     /// Whether the model supports vision
     public var supportsVision: Bool?
     /// Policy configuration state
@@ -615,6 +619,8 @@ public struct SessionModelInfo: Codable, Sendable {
         case provider
         case name
         case maxContextWindow
+        case maxOutputTokens
+        case maxPromptTokens
         case supportsVision
         case policyState
         case configSchema
@@ -626,6 +632,8 @@ public struct SessionModelInfo: Codable, Sendable {
         provider: String,
         name: String,
         maxContextWindow: Int? = nil,
+        maxOutputTokens: Int? = nil,
+        maxPromptTokens: Int? = nil,
         supportsVision: Bool? = nil,
         policyState: PolicyState? = nil,
         configSchema: ConfigSchema? = nil,
@@ -635,6 +643,8 @@ public struct SessionModelInfo: Codable, Sendable {
         self.provider = provider
         self.name = name
         self.maxContextWindow = maxContextWindow
+        self.maxOutputTokens = maxOutputTokens
+        self.maxPromptTokens = maxPromptTokens
         self.supportsVision = supportsVision
         self.policyState = policyState
         self.configSchema = configSchema

clients/swift/CHANGELOG.md

@@ -19,6 +19,8 @@ the tag matches the version pinned in [`VERSION`](VERSION).
 
 ### Added
 
+- `SessionModelInfo.maxOutputTokens` and `SessionModelInfo.maxPromptTokens`
+  optional fields for communicating model token limits.
 - `SessionSummary.meta` (`_meta` on the wire) optional provider metadata field
   for lightweight session-list presentation hints.
 

clients/typescript/CHANGELOG.md

@@ -22,6 +22,8 @@ hotfix escape hatch.
 
 ### Added
 
+- `SessionModelInfo.maxOutputTokens` and `SessionModelInfo.maxPromptTokens`
+  optional fields for communicating model token limits.
 - `SessionSummary._meta` optional provider metadata field for lightweight
   session-list presentation hints.
 

schema/actions.schema.json

@@ -2441,6 +2441,14 @@
           "type": "number",
           "description": "Maximum context window size"
         },
+        "maxOutputTokens": {
+          "type": "number",
+          "description": "Maximum number of output tokens the model can generate"
+        },
+        "maxPromptTokens": {
+          "type": "number",
+          "description": "Maximum number of prompt (input) tokens the model accepts"
+        },
         "supportsVision": {
           "type": "boolean",
           "description": "Whether the model supports vision"

schema/commands.schema.json

@@ -1779,6 +1779,14 @@
           "type": "number",
           "description": "Maximum context window size"
         },
+        "maxOutputTokens": {
+          "type": "number",
+          "description": "Maximum number of output tokens the model can generate"
+        },
+        "maxPromptTokens": {
+          "type": "number",
+          "description": "Maximum number of prompt (input) tokens the model accepts"
+        },
         "supportsVision": {
           "type": "boolean",
           "description": "Whether the model supports vision"

schema/errors.schema.json

@@ -631,6 +631,14 @@
           "type": "number",
           "description": "Maximum context window size"
         },
+        "maxOutputTokens": {
+          "type": "number",
+          "description": "Maximum number of output tokens the model can generate"
+        },
+        "maxPromptTokens": {
+          "type": "number",
+          "description": "Maximum number of prompt (input) tokens the model accepts"
+        },
         "supportsVision": {
           "type": "boolean",
           "description": "Whether the model supports vision"

schema/notifications.schema.json

@@ -765,6 +765,14 @@
           "type": "number",
           "description": "Maximum context window size"
         },
+        "maxOutputTokens": {
+          "type": "number",
+          "description": "Maximum number of output tokens the model can generate"
+        },
+        "maxPromptTokens": {
+          "type": "number",
+          "description": "Maximum number of prompt (input) tokens the model accepts"
+        },
         "supportsVision": {
           "type": "boolean",
           "description": "Whether the model supports vision"

schema/state.schema.json

@@ -542,6 +542,14 @@
           "type": "number",
           "description": "Maximum context window size"
         },
+        "maxOutputTokens": {
+          "type": "number",
+          "description": "Maximum number of output tokens the model can generate"
+        },
+        "maxPromptTokens": {
+          "type": "number",
+          "description": "Maximum number of prompt (input) tokens the model accepts"
+        },
         "supportsVision": {
           "type": "boolean",
           "description": "Whether the model supports vision"

types/channels-root/state.ts

@@ -98,6 +98,10 @@ export interface SessionModelInfo {
   name: string;
   /** Maximum context window size */
   maxContextWindow?: number;
+  /** Maximum number of output tokens the model can generate */
+  maxOutputTokens?: number;
+  /** Maximum number of prompt (input) tokens the model accepts */
+  maxPromptTokens?: number;
   /** Whether the model supports vision */
   supportsVision?: boolean;
   /** Policy configuration state */