SDKs: expose MCP server instruction policy

dotnet/src/Client.cs

@@ -1250,6 +1250,7 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig config, Cance
                 config.Streaming is true ? true : null,
                 config.IncludeSubAgentStreamingEvents,
                 config.McpServers,
+                config.AllowAllMcpServerInstructions,
                 config.McpOAuthTokenStorage,
                 config.AuthClientIdMetadataUrl,
                 "direct",
@@ -1503,6 +1504,7 @@ public async Task<CopilotSession> ResumeSessionAsync(string sessionId, ResumeSes
                 config.Streaming is true ? true : null,
                 config.IncludeSubAgentStreamingEvents,
                 config.McpServers,
+                config.AllowAllMcpServerInstructions,
                 config.McpOAuthTokenStorage,
                 config.AuthClientIdMetadataUrl,
                 "direct",
@@ -3034,6 +3036,7 @@ internal record CreateSessionRequest(
         bool? Streaming,
         bool? IncludeSubAgentStreamingEvents,
         IDictionary<string, McpServerConfig>? McpServers,
+        bool? AllowAllMcpServerInstructions,
         McpOAuthTokenStorageMode? McpOAuthTokenStorage,
         string? AuthClientIdMetadataUrl,
         string? EnvValueMode,
@@ -3164,6 +3167,7 @@ internal record ResumeSessionRequest(
         bool? Streaming,
         bool? IncludeSubAgentStreamingEvents,
         IDictionary<string, McpServerConfig>? McpServers,
+        bool? AllowAllMcpServerInstructions,
         McpOAuthTokenStorageMode? McpOAuthTokenStorage,
         string? AuthClientIdMetadataUrl,
         string? EnvValueMode,

dotnet/src/Types.cs

@@ -3288,6 +3288,7 @@ protected SessionConfigBase(SessionConfigBase? other)
         DisabledSkills = other.DisabledSkills is not null ? [.. other.DisabledSkills] : null;
         IncludedBuiltinSkills = other.IncludedBuiltinSkills is not null ? [.. other.IncludedBuiltinSkills] : null;
         DisabledMcpServers = other.DisabledMcpServers is not null ? [.. other.DisabledMcpServers] : null;
+        AllowAllMcpServerInstructions = other.AllowAllMcpServerInstructions;
         EnableCitations = other.EnableCitations;
         EnableFileChangeTracking = other.EnableFileChangeTracking;
         EnableConfigDiscovery = other.EnableConfigDiscovery;
@@ -3716,6 +3717,13 @@ protected SessionConfigBase(SessionConfigBase? other)
     /// </summary>
     public IDictionary<string, McpServerConfig>? McpServers { get; set; }
 
+    /// <summary>
+    /// Whether instructions from every configured MCP server are included in the
+    /// system prompt. Enabling this broadens the default trust boundary; only use
+    /// it with trusted servers. When null, the runtime default applies.
+    /// </summary>
+    public bool? AllowAllMcpServerInstructions { get; set; }
+
     /// <summary>
     /// Controls how MCP OAuth tokens are stored for this session.
     /// Default: <see cref="McpOAuthTokenStorageMode.InMemory"/> for safe multitenant behavior.

dotnet/test/Unit/ClientSessionLifetimeTests.cs

@@ -512,6 +512,54 @@ public async Task SessionRequests_Serialize_CapiAutoTier(AutoTier tier, string e
         }
     }
 
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public async Task SessionRequests_Forward_McpServerInstructionPolicy(bool value)
+    {
+        await using var server = await FakeCopilotServer.StartAsync();
+        await using var client = new CopilotClient(new CopilotClientOptions { Connection = RuntimeConnection.ForUri(server.Url) });
+
+        await using var created = await client.CreateSessionAsync(new SessionConfig
+        {
+            AllowAllMcpServerInstructions = value,
+            OnPermissionRequest = PermissionHandler.ApproveAll
+        });
+        await using var resumed = await client.ResumeSessionAsync("resume-with-mcp-instruction-policy", new ResumeSessionConfig
+        {
+            AllowAllMcpServerInstructions = value,
+            OnPermissionRequest = PermissionHandler.ApproveAll
+        });
+
+        foreach (var method in new[] { "session.create", "session.resume" })
+        {
+            var request = Assert.Single(server.Requests, request => request.Method == method);
+            Assert.Equal(value, request.Params.GetProperty("allowAllMcpServerInstructions").GetBoolean());
+        }
+    }
+
+    [Fact]
+    public async Task SessionRequests_Omit_McpServerInstructionPolicy_WhenUnset()
+    {
+        await using var server = await FakeCopilotServer.StartAsync();
+        await using var client = new CopilotClient(new CopilotClientOptions { Connection = RuntimeConnection.ForUri(server.Url) });
+
+        await using var created = await client.CreateSessionAsync(new SessionConfig
+        {
+            OnPermissionRequest = PermissionHandler.ApproveAll
+        });
+        await using var resumed = await client.ResumeSessionAsync("resume-without-mcp-instruction-policy", new ResumeSessionConfig
+        {
+            OnPermissionRequest = PermissionHandler.ApproveAll
+        });
+
+        foreach (var method in new[] { "session.create", "session.resume" })
+        {
+            var request = Assert.Single(server.Requests, request => request.Method == method);
+            Assert.False(request.Params.TryGetProperty("allowAllMcpServerInstructions", out _));
+        }
+    }
+
     [Theory]
     [InlineData("efficiency")]
     [InlineData("balance")]

go/client.go

@@ -902,6 +902,7 @@ func (c *Client) CreateSession(ctx context.Context, config *SessionConfig) (*Ses
 	req.WorkingDirectory = config.WorkingDirectory
 	req.AdditionalDirectories = config.AdditionalDirectories
 	req.MCPServers = config.MCPServers
+	req.AllowAllMCPServerInstructions = config.AllowAllMCPServerInstructions
 	req.MCPOAuthTokenStorage = config.MCPOAuthTokenStorage
 	req.AuthClientIDMetadataURL = config.AuthClientIDMetadataURL
 	req.EnvValueMode = "direct"
@@ -1322,6 +1323,7 @@ func (c *Client) ResumeSessionWithOptions(ctx context.Context, sessionID string,
 	}
 	req.ContinuePendingWork = config.ContinuePendingWork
 	req.MCPServers = config.MCPServers
+	req.AllowAllMCPServerInstructions = config.AllowAllMCPServerInstructions
 	req.MCPOAuthTokenStorage = config.MCPOAuthTokenStorage
 	req.AuthClientIDMetadataURL = config.AuthClientIDMetadataURL
 	req.EnvValueMode = "direct"

go/client_test.go

@@ -1970,6 +1970,43 @@ func TestSessionRequests_PluginDirectoriesAndLargeOutput(t *testing.T) {
 	})
 }
 
+func TestSessionRequests_AllowAllMCPServerInstructions(t *testing.T) {
+	for _, tc := range []struct {
+		name  string
+		value *bool
+		want  any
+	}{
+		{name: "true", value: Bool(true), want: true},
+		{name: "false", value: Bool(false), want: false},
+		{name: "omitted", value: nil, want: nil},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			requests := []any{
+				createSessionRequest{AllowAllMCPServerInstructions: tc.value},
+				resumeSessionRequest{SessionID: "s1", AllowAllMCPServerInstructions: tc.value},
+			}
+			for _, request := range requests {
+				data, err := json.Marshal(request)
+				if err != nil {
+					t.Fatalf("Failed to marshal: %v", err)
+				}
+				var payload map[string]any
+				if err := json.Unmarshal(data, &payload); err != nil {
+					t.Fatalf("Failed to unmarshal: %v", err)
+				}
+				got, present := payload["allowAllMcpServerInstructions"]
+				if tc.value == nil {
+					if present {
+						t.Fatalf("Expected policy to be omitted, got %v", got)
+					}
+				} else if !present || got != tc.want {
+					t.Fatalf("Expected policy %v, got %v", tc.want, got)
+				}
+			}
+		})
+	}
+}
+
 func TestSessionRequests_Memory(t *testing.T) {
 	t.Run("create includes memory in JSON when enabled", func(t *testing.T) {
 		req := createSessionRequest{Memory: &MemoryConfiguration{Enabled: true}}

go/types.go

@@ -1490,6 +1490,11 @@ type SessionConfig struct {
 	ModelCapabilities *rpc.ModelCapabilitiesOverride
 	// MCPServers configures MCP servers for the session
 	MCPServers map[string]MCPServerConfig
+	// AllowAllMCPServerInstructions controls whether instructions from every
+	// configured MCP server are included in the system prompt. Enabling this
+	// broadens the default trust boundary; only use it with trusted servers.
+	// Nil leaves the runtime default unchanged.
+	AllowAllMCPServerInstructions *bool
 	// MCPOAuthTokenStorage controls how MCP OAuth tokens are stored for this session.
 	// When empty, the runtime default ("in-memory") is used.
 	MCPOAuthTokenStorage string
@@ -2053,6 +2058,11 @@ type ResumeSessionConfig struct {
 	IncludeSubAgentStreamingEvents *bool
 	// MCPServers configures MCP servers for the session
 	MCPServers map[string]MCPServerConfig
+	// AllowAllMCPServerInstructions controls whether instructions from every
+	// configured MCP server are included in the system prompt. Enabling this
+	// broadens the default trust boundary; only use it with trusted servers.
+	// Nil leaves the runtime default unchanged.
+	AllowAllMCPServerInstructions *bool
 	// MCPOAuthTokenStorage controls how MCP OAuth tokens are stored for this session.
 	// When empty, the runtime default ("in-memory") is used.
 	MCPOAuthTokenStorage string
@@ -2650,6 +2660,7 @@ type createSessionRequest struct {
 	IncludeSubAgentStreamingEvents     *bool                                  `json:"includeSubAgentStreamingEvents,omitempty"`
 	EnableGitHubTelemetryForwarding    *bool                                  `json:"enableGitHubTelemetryForwarding,omitempty"`
 	MCPServers                         map[string]MCPServerConfig             `json:"mcpServers,omitempty"`
+	AllowAllMCPServerInstructions      *bool                                  `json:"allowAllMcpServerInstructions,omitempty"`
 	MCPOAuthTokenStorage               string                                 `json:"mcpOAuthTokenStorage,omitempty"`
 	AuthClientIDMetadataURL            string                                 `json:"authClientIdMetadataUrl,omitempty"`
 	EnvValueMode                       string                                 `json:"envValueMode,omitempty"`
@@ -2762,6 +2773,7 @@ type resumeSessionRequest struct {
 	IncludeSubAgentStreamingEvents     *bool                                  `json:"includeSubAgentStreamingEvents,omitempty"`
 	EnableGitHubTelemetryForwarding    *bool                                  `json:"enableGitHubTelemetryForwarding,omitempty"`
 	MCPServers                         map[string]MCPServerConfig             `json:"mcpServers,omitempty"`
+	AllowAllMCPServerInstructions      *bool                                  `json:"allowAllMcpServerInstructions,omitempty"`
 	MCPOAuthTokenStorage               string                                 `json:"mcpOAuthTokenStorage,omitempty"`
 	AuthClientIDMetadataURL            string                                 `json:"authClientIdMetadataUrl,omitempty"`
 	EnvValueMode                       string                                 `json:"envValueMode,omitempty"`

java/sdk/src/main/java/com/github/copilot/SessionRequestBuilder.java

@@ -148,6 +148,7 @@ static CreateSessionRequest buildCreateRequest(SessionConfig config, String sess
         }
         config.getIncludeSubAgentStreamingEvents().ifPresent(request::setIncludeSubAgentStreamingEvents);
         request.setMcpServers(config.getMcpServers());
+        request.setAllowAllMcpServerInstructions(config.getAllowAllMcpServerInstructions());
         request.setMcpOAuthTokenStorage(config.getMcpOAuthTokenStorage());
         request.setAuthClientIdMetadataUrl(config.getAuthClientIdMetadataUrl());
         request.setCustomAgents(config.getCustomAgents());
@@ -304,6 +305,7 @@ static ResumeSessionRequest buildResumeRequest(String sessionId, ResumeSessionCo
         }
         config.getIncludeSubAgentStreamingEvents().ifPresent(request::setIncludeSubAgentStreamingEvents);
         request.setMcpServers(config.getMcpServers());
+        request.setAllowAllMcpServerInstructions(config.getAllowAllMcpServerInstructions());
         request.setMcpOAuthTokenStorage(config.getMcpOAuthTokenStorage());
         request.setAuthClientIdMetadataUrl(config.getAuthClientIdMetadataUrl());
         request.setCustomAgents(config.getCustomAgents());

java/sdk/src/main/java/com/github/copilot/rpc/CreateSessionRequest.java

@@ -116,6 +116,9 @@ public final class CreateSessionRequest {
     @JsonProperty("mcpServers")
     private Map<String, McpServerConfig> mcpServers;
 
+    @JsonProperty("allowAllMcpServerInstructions")
+    private Boolean allowAllMcpServerInstructions;
+
     @JsonProperty("mcpOAuthTokenStorage")
     private String mcpOAuthTokenStorage;
 
@@ -594,6 +597,16 @@ public void setMcpServers(Map<String, McpServerConfig> mcpServers) {
         this.mcpServers = mcpServers;
     }
 
+    /** Gets the MCP server instruction policy. @return the policy value */
+    public Boolean getAllowAllMcpServerInstructions() {
+        return allowAllMcpServerInstructions;
+    }
+
+    /** Sets the MCP server instruction policy. @param value the policy value */
+    public void setAllowAllMcpServerInstructions(Boolean value) {
+        this.allowAllMcpServerInstructions = value;
+    }
+
     /** Gets MCP OAuth token storage mode. @return the storage mode */
     public String getMcpOAuthTokenStorage() {
         return mcpOAuthTokenStorage;

java/sdk/src/main/java/com/github/copilot/rpc/ResumeSessionConfig.java

@@ -85,6 +85,7 @@ public class ResumeSessionConfig {
     private boolean streaming;
     private Boolean includeSubAgentStreamingEvents;
     private Map<String, McpServerConfig> mcpServers;
+    private Boolean allowAllMcpServerInstructions;
     private String mcpOAuthTokenStorage;
     private String authClientIdMetadataUrl;
     private List<CustomAgentConfig> customAgents;
@@ -1397,6 +1398,30 @@ public ResumeSessionConfig setMcpServers(Map<String, McpServerConfig> mcpServers
         return this;
     }
 
+    /**
+     * Gets whether instructions from every configured MCP server are included in
+     * the system prompt.
+     *
+     * @return the policy value, or {@code null} when the runtime default applies
+     */
+    public Boolean getAllowAllMcpServerInstructions() {
+        return allowAllMcpServerInstructions;
+    }
+
+    /**
+     * Controls whether instructions from every configured MCP server are included
+     * in the system prompt. Enabling this broadens the default trust boundary; only
+     * use it with trusted servers.
+     *
+     * @param allowAllMcpServerInstructions
+     *            the explicit policy value, or {@code null} for the runtime default
+     * @return this config instance for method chaining
+     */
+    public ResumeSessionConfig setAllowAllMcpServerInstructions(Boolean allowAllMcpServerInstructions) {
+        this.allowAllMcpServerInstructions = allowAllMcpServerInstructions;
+        return this;
+    }
+
     /**
      * Gets the MCP OAuth token storage mode.
      *
@@ -2143,6 +2168,7 @@ public ResumeSessionConfig clone() {
         copy.streaming = this.streaming;
         copy.includeSubAgentStreamingEvents = this.includeSubAgentStreamingEvents;
         copy.mcpServers = this.mcpServers != null ? new java.util.HashMap<>(this.mcpServers) : null;
+        copy.allowAllMcpServerInstructions = this.allowAllMcpServerInstructions;
         copy.mcpOAuthTokenStorage = this.mcpOAuthTokenStorage;
         copy.authClientIdMetadataUrl = this.authClientIdMetadataUrl;
         copy.customAgents = this.customAgents != null ? new ArrayList<>(this.customAgents) : null;

java/sdk/src/main/java/com/github/copilot/rpc/ResumeSessionRequest.java

@@ -159,6 +159,9 @@ public final class ResumeSessionRequest {
     @JsonProperty("mcpServers")
     private Map<String, McpServerConfig> mcpServers;
 
+    @JsonProperty("allowAllMcpServerInstructions")
+    private Boolean allowAllMcpServerInstructions;
+
     @JsonProperty("mcpOAuthTokenStorage")
     private String mcpOAuthTokenStorage;
 
@@ -820,6 +823,16 @@ public void setMcpServers(Map<String, McpServerConfig> mcpServers) {
         this.mcpServers = mcpServers;
     }
 
+    /** Gets the MCP server instruction policy. @return the policy value */
+    public Boolean getAllowAllMcpServerInstructions() {
+        return allowAllMcpServerInstructions;
+    }
+
+    /** Sets the MCP server instruction policy. @param value the policy value */
+    public void setAllowAllMcpServerInstructions(Boolean value) {
+        this.allowAllMcpServerInstructions = value;
+    }
+
     /** Gets MCP OAuth token storage mode. @return the storage mode */
     public String getMcpOAuthTokenStorage() {
         return mcpOAuthTokenStorage;

java/sdk/src/main/java/com/github/copilot/rpc/SessionConfig.java

@@ -74,6 +74,7 @@ public class SessionConfig {
     private boolean streaming;
     private Boolean includeSubAgentStreamingEvents;
     private Map<String, McpServerConfig> mcpServers;
+    private Boolean allowAllMcpServerInstructions;
     private String mcpOAuthTokenStorage;
     private String authClientIdMetadataUrl;
     private List<CustomAgentConfig> customAgents;
@@ -1050,6 +1051,30 @@ public SessionConfig setMcpServers(Map<String, McpServerConfig> mcpServers) {
         return this;
     }
 
+    /**
+     * Gets whether instructions from every configured MCP server are included in
+     * the system prompt.
+     *
+     * @return the policy value, or {@code null} when the runtime default applies
+     */
+    public Boolean getAllowAllMcpServerInstructions() {
+        return allowAllMcpServerInstructions;
+    }
+
+    /**
+     * Controls whether instructions from every configured MCP server are included
+     * in the system prompt. Enabling this broadens the default trust boundary; only
+     * use it with trusted servers.
+     *
+     * @param allowAllMcpServerInstructions
+     *            the explicit policy value, or {@code null} for the runtime default
+     * @return this config instance for method chaining
+     */
+    public SessionConfig setAllowAllMcpServerInstructions(Boolean allowAllMcpServerInstructions) {
+        this.allowAllMcpServerInstructions = allowAllMcpServerInstructions;
+        return this;
+    }
+
     /**
      * Gets the MCP OAuth token storage mode.
      *
@@ -2272,6 +2297,7 @@ public SessionConfig clone() {
         copy.streaming = this.streaming;
         copy.includeSubAgentStreamingEvents = this.includeSubAgentStreamingEvents;
         copy.mcpServers = this.mcpServers != null ? new java.util.HashMap<>(this.mcpServers) : null;
+        copy.allowAllMcpServerInstructions = this.allowAllMcpServerInstructions;
         copy.mcpOAuthTokenStorage = this.mcpOAuthTokenStorage;
         copy.authClientIdMetadataUrl = this.authClientIdMetadataUrl;
         copy.customAgents = this.customAgents != null ? new ArrayList<>(this.customAgents) : null;