feat(mcp): upgrade client SDK to v2 (#39247)

Co-authored-by: Matt Carey <mcarey@cloudflare.com>

packages/opencode/src/cli/cmd/mcp.ts

@@ -2,13 +2,10 @@ import { cmd } from "./cmd"
 import { ConfigV1 } from "@opencode-ai/core/v1/config/config"
 import { effectCmd } from "../effect-cmd"
 import { Cause } from "effect"
-import { Client } from "@modelcontextprotocol/sdk/client/index.js"
-import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js"
-import { UnauthorizedError } from "@modelcontextprotocol/sdk/client/auth.js"
-import { LATEST_PROTOCOL_VERSION } from "@modelcontextprotocol/sdk/types.js"
+import { Client, StreamableHTTPClientTransport, UnauthorizedError } from "@modelcontextprotocol/client"
 import * as prompts from "@clack/prompts"
 import { UI } from "../ui"
-import { MCP } from "../../mcp"
+import { CLIENT_OPTIONS, MCP } from "../../mcp"
 import { McpAuth } from "../../mcp/auth"
 import { McpOAuthProvider } from "../../mcp/oauth-provider"
 import { Config } from "@/config/config"
@@ -731,107 +728,52 @@ export const McpDebugCommand = effectCmd({
       const spinner = prompts.spinner()
       spinner.start("Testing connection...")
 
-      // Test basic HTTP connectivity first
-      try {
-        const response = await fetch(serverConfig.url, {
-          method: "POST",
-          headers: {
-            ...serverConfig.headers,
-            "Content-Type": "application/json",
-            Accept: "application/json, text/event-stream",
+      const oauthConfig = typeof serverConfig.oauth === "object" ? serverConfig.oauth : undefined
+      let authorizationUrl: URL | undefined
+      const authProvider = new McpOAuthProvider(
+        serverName,
+        serverConfig.url,
+        {
+          clientId: oauthConfig?.clientId,
+          clientSecret: oauthConfig?.clientSecret,
+          scope: oauthConfig?.scope,
+          redirectUri: oauthConfig?.redirectUri,
+        },
+        {
+          onRedirect: async (url) => {
+            authorizationUrl = url
           },
-          body: JSON.stringify({
-            jsonrpc: "2.0",
-            method: "initialize",
-            params: {
-              protocolVersion: LATEST_PROTOCOL_VERSION,
-              capabilities: {},
-              clientInfo: { name: "opencode-debug", version: InstallationVersion },
-            },
-            id: 1,
-          }),
-        })
+        },
+        auth,
+      )
+      const transport = new StreamableHTTPClientTransport(new URL(serverConfig.url), {
+        authProvider,
+        requestInit: serverConfig.headers ? { headers: serverConfig.headers } : undefined,
+      })
+      const client = new Client({ name: "opencode-debug", version: InstallationVersion }, CLIENT_OPTIONS)
 
-        spinner.stop(`HTTP response: ${response.status} ${response.statusText}`)
-
-        // Check for WWW-Authenticate header
-        const wwwAuth = response.headers.get("www-authenticate")
-        if (wwwAuth) {
-          prompts.log.info(`WWW-Authenticate: ${wwwAuth}`)
-        }
-
-        if (response.status === 401) {
-          prompts.log.info("Initial unauthenticated check returned 401, so this server requires OAuth")
-
-          // Try to discover OAuth metadata
-          const oauthConfig = typeof serverConfig.oauth === "object" ? serverConfig.oauth : undefined
-          const authProvider = new McpOAuthProvider(
-            serverName,
-            serverConfig.url,
-            {
-              clientId: oauthConfig?.clientId,
-              clientSecret: oauthConfig?.clientSecret,
-              scope: oauthConfig?.scope,
-              redirectUri: oauthConfig?.redirectUri,
-            },
-            {
-              onRedirect: async () => {},
-            },
-            auth,
-          )
-
-          prompts.log.info("Testing OAuth flow (without completing authorization)...")
-
-          // Try creating transport with auth provider to trigger discovery
-          const transport = new StreamableHTTPClientTransport(new URL(serverConfig.url), {
-            authProvider,
-            requestInit: serverConfig.headers ? { headers: serverConfig.headers } : undefined,
-          })
-
-          try {
-            const client = new Client({
-              name: "opencode-debug",
-              version: InstallationVersion,
-            })
-            await client.connect(transport)
-            prompts.log.success("Connection successful (already authenticated)")
-            await client.close()
-          } catch (error) {
-            if (error instanceof UnauthorizedError) {
-              prompts.log.info(`OAuth flow triggered: ${error.message}`)
-
-              // Check if dynamic registration would be attempted
-              const clientInfo = await authProvider.clientInformation()
-              if (clientInfo) {
-                prompts.log.info(`Client ID available: ${clientInfo.client_id}`)
-              } else {
-                prompts.log.info("No client ID - dynamic registration will be attempted")
-              }
-            } else {
-              prompts.log.error(`Connection error: ${error instanceof Error ? error.message : String(error)}`)
-            }
-          }
-        } else if (response.status >= 200 && response.status < 300) {
-          prompts.log.success("Server responded successfully (no auth required or already authenticated)")
-          const body = await response.text()
-          try {
-            const json = JSON.parse(body)
-            if (json.result?.serverInfo) {
-              prompts.log.info(`Server info: ${JSON.stringify(json.result.serverInfo)}`)
-            }
-          } catch {
-            // Not JSON, ignore
-          }
-        } else {
-          prompts.log.warn(`Unexpected status: ${response.status}`)
-          const body = await response.text().catch(() => "")
-          if (body) {
-            prompts.log.info(`Response body: ${body.substring(0, 500)}`)
-          }
-        }
+      try {
+        await client.connect(transport)
+        spinner.stop("SDK connection successful")
+        prompts.log.success(
+          `Connected using MCP ${client.getNegotiatedProtocolVersion() ?? "unknown"} (${client.getProtocolEra() ?? "unknown"})`,
+        )
+        const serverInfo = client.getServerVersion()
+        if (serverInfo) prompts.log.info(`Server info: ${JSON.stringify(serverInfo)}`)
       } catch (error) {
-        spinner.stop("Connection failed", 1)
-        prompts.log.error(`Error: ${error instanceof Error ? error.message : String(error)}`)
+        if (error instanceof UnauthorizedError) {
+          spinner.stop("OAuth required")
+          prompts.log.info(`OAuth flow triggered: ${error.message}`)
+          if (authorizationUrl) prompts.log.info(`Authorization URL: ${authorizationUrl}`)
+          const clientInfo = await authProvider.clientInformation()
+          if (clientInfo) prompts.log.info(`Client ID available: ${clientInfo.client_id}`)
+          if (!clientInfo) prompts.log.info("No client ID - dynamic registration will be attempted")
+        } else {
+          spinner.stop("Connection failed", 1)
+          prompts.log.error(`Error: ${error instanceof Error ? error.message : String(error)}`)
+        }
+      } finally {
+        await client.close().catch(() => {})
       }
 
       prompts.outro("Debug complete")

packages/opencode/src/mcp/auth.ts

@@ -11,6 +11,7 @@ export const Tokens = Schema.Struct({
   refreshToken: Schema.mutableKey(Schema.optional(Schema.String)),
   expiresAt: Schema.mutableKey(Schema.optional(Schema.Number)),
   scope: Schema.mutableKey(Schema.optional(Schema.String)),
+  issuer: Schema.mutableKey(Schema.optional(Schema.String)),
 })
 export type Tokens = Schema.Schema.Type<typeof Tokens>
 
@@ -19,6 +20,9 @@ export const ClientInfo = Schema.Struct({
   clientSecret: Schema.mutableKey(Schema.optional(Schema.String)),
   clientIdIssuedAt: Schema.mutableKey(Schema.optional(Schema.Number)),
   clientSecretExpiresAt: Schema.mutableKey(Schema.optional(Schema.Number)),
+  redirectUris: Schema.mutableKey(Schema.optional(Schema.Array(Schema.String))),
+  issuer: Schema.mutableKey(Schema.optional(Schema.String)),
+  configPreRegistered: Schema.mutableKey(Schema.optional(Schema.Boolean)),
 })
 export type ClientInfo = Schema.Schema.Type<typeof ClientInfo>
 

packages/opencode/src/mcp/catalog.ts

@@ -1,40 +1,8 @@
-import { Client } from "@modelcontextprotocol/sdk/client/index.js"
-import {
-  CallToolResultSchema,
-  ListToolsResultSchema,
-  ToolSchema,
-  type Tool as MCPToolDef,
-} from "@modelcontextprotocol/sdk/types.js"
+import { Client, type Tool as MCPToolDef } from "@modelcontextprotocol/client"
 import { dynamicTool, jsonSchema, type JSONSchema7, type Tool } from "ai"
 import { Effect } from "effect"
 
 const DEFAULT_TIMEOUT = 30_000
-const MAX_LIST_PAGES = 1_000
-
-const TolerantListToolsResultSchema = ListToolsResultSchema.extend({
-  tools: ToolSchema.omit({ outputSchema: true }).array(),
-})
-
-export async function paginate<T, R extends { nextCursor?: string }>(
-  list: (cursor?: string) => Promise<R>,
-  items: (result: R) => T[],
-) {
-  const result: T[] = []
-  const cursors = new Set<string>()
-  let cursor: string | undefined
-
-  for (let page = 0; page < MAX_LIST_PAGES; page++) {
-    const page = await list(cursor)
-    result.push(...items(page))
-    if (page.nextCursor === undefined) return result
-    if (cursors.has(page.nextCursor)) throw new Error(`MCP list returned duplicate cursor: ${page.nextCursor}`)
-    cursors.add(page.nextCursor)
-    cursor = page.nextCursor
-  }
-
-  throw new Error(`MCP list exceeded ${MAX_LIST_PAGES} pages`)
-}
-
 export function defs(client: Client, timeout?: number) {
   return listTools(client, timeout ?? DEFAULT_TIMEOUT).pipe(Effect.catch(() => Effect.void))
 }
@@ -56,7 +24,6 @@ export function convertTool(mcpTool: MCPToolDef, client: Client, timeout?: numbe
           name: mcpTool.name,
           arguments: (args || {}) as Record<string, unknown>,
         },
-        CallToolResultSchema,
         {
           resetTimeoutOnProgress: true,
           signal: options.abortSignal,
@@ -118,53 +85,26 @@ export const sanitize = (value: string) => value.replace(/[^a-zA-Z0-9_-]/g, "_")
 
 export const toolName = (clientName: string, name: string) => sanitize(clientName) + "_" + sanitize(name)
 
-export function prompts(client: Client, timeout?: number) {
-  if (!client.getServerCapabilities()?.prompts) return Promise.resolve([])
-  return paginate(
-    (cursor) => client.listPrompts(cursor === undefined ? undefined : { cursor }, { timeout }),
-    (result) => result.prompts,
-  )
+export async function prompts(client: Client, timeout?: number) {
+  if (!client.getServerCapabilities()?.prompts) return []
+  return (await client.listPrompts(undefined, { timeout })).prompts
 }
 
-export function resources(client: Client, timeout?: number) {
-  if (!client.getServerCapabilities()?.resources) return Promise.resolve([])
-  return paginate(
-    (cursor) => client.listResources(cursor === undefined ? undefined : { cursor }, { timeout }),
-    (result) => result.resources,
-  )
+export async function resources(client: Client, timeout?: number) {
+  if (!client.getServerCapabilities()?.resources) return []
+  return (await client.listResources(undefined, { timeout })).resources
 }
 
-export function resourceTemplates(client: Client, timeout?: number) {
-  if (!client.getServerCapabilities()?.resources) return Promise.resolve([])
-  return paginate(
-    (cursor) => client.listResourceTemplates(cursor === undefined ? undefined : { cursor }, { timeout }),
-    (result) => result.resourceTemplates,
-  )
+export async function resourceTemplates(client: Client, timeout?: number) {
+  if (!client.getServerCapabilities()?.resources) return []
+  return (await client.listResourceTemplates(undefined, { timeout })).resourceTemplates
 }
 
 function listTools(client: Client, timeout: number) {
   return Effect.tryPromise({
-    try: () =>
-      paginate(
-        async (cursor) => {
-          const params = cursor === undefined ? undefined : { cursor }
-          try {
-            return await client.listTools(params, { timeout })
-          } catch (error) {
-            if (!(error instanceof Error) || !isOutputSchemaValidationError(error)) throw error
-            return client.request({ method: "tools/list", params }, TolerantListToolsResultSchema, { timeout })
-          }
-        },
-        (result) => result.tools,
-      ),
+    try: async () => (await client.listTools(undefined, { timeout })).tools,
     catch: (error) => (error instanceof Error ? error : new Error(String(error))),
   })
 }
 
-function isOutputSchemaValidationError(error: Error) {
-  return /can't resolve reference|resolves to more than one schema|outputSchema|schema.*reference|reference.*schema/i.test(
-    error.message,
-  )
-}
-
 export * as McpCatalog from "./catalog"

packages/opencode/src/mcp/index.ts

@@ -3,18 +3,18 @@ import { pathToFileURL } from "node:url"
 import { LayerNode } from "@opencode-ai/core/effect/layer-node"
 import { ConfigV1 } from "@opencode-ai/core/v1/config/config"
 import { serviceUse } from "@opencode-ai/core/effect/service-use"
-import { Client, type ClientOptions } from "@modelcontextprotocol/sdk/client/index.js"
-import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js"
-import { SSEClientTransport } from "@modelcontextprotocol/sdk/client/sse.js"
-import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js"
-import { UnauthorizedError } from "@modelcontextprotocol/sdk/client/auth.js"
 import {
-  ListRootsRequestSchema,
+  Client,
+  type ClientOptions,
+  StreamableHTTPClientTransport,
+  SSEClientTransport,
+  UnauthorizedError,
+  RegistrationRejectedError,
+  SdkHttpError,
   type LoggingMessageNotification,
-  LoggingMessageNotificationSchema,
   type Tool as MCPToolDef,
-  ToolListChangedNotificationSchema,
-} from "@modelcontextprotocol/sdk/types.js"
+} from "@modelcontextprotocol/client"
+import { StdioClientTransport } from "@modelcontextprotocol/client/stdio"
 import { Config } from "@/config/config"
 import { ConfigMCPV1 } from "@opencode-ai/core/v1/config/mcp"
 import { NamedError } from "@opencode-ai/core/util/error"
@@ -36,7 +36,7 @@ import { McpEvent } from "@opencode-ai/schema/mcp-event"
 import { McpBrowser } from "./browser"
 
 const DEFAULT_TIMEOUT = 30_000
-const CLIENT_OPTIONS = {
+export const CLIENT_OPTIONS = {
   capabilities: {
     // https://github.com/anomalyco/opencode/issues/11948
     // sampling: {},
@@ -47,6 +47,8 @@ const CLIENT_OPTIONS = {
     // https://github.com/anomalyco/opencode/issues/28567
     // tasks: {},
   },
+  versionNegotiation: { mode: "auto" },
+  listMaxPages: 1_000,
 } satisfies ClientOptions
 
 export const Resource = Schema.Struct({
@@ -70,13 +72,19 @@ export class NotFoundError extends Schema.TaggedErrorClass<NotFoundError>()("MCP
   name: Schema.String,
 }) {}
 
-type MCPClient = Client
+type MCPClient = Client & { onToolsChanged?: (error: Error | null) => void }
 
 function createClient(directory: string) {
-  const client = new Client({ name: "opencode", version: InstallationVersion }, CLIENT_OPTIONS)
-  client.setRequestHandler(ListRootsRequestSchema, () =>
-    Promise.resolve({ roots: [{ uri: pathToFileURL(directory).href }] }),
+  const client: MCPClient = new Client(
+    { name: "opencode", version: InstallationVersion },
+    {
+      ...CLIENT_OPTIONS,
+      listChanged: {
+        tools: { autoRefresh: false, onChanged: (error) => client.onToolsChanged?.(error) },
+      },
+    },
   )
+  client.setRequestHandler("roots/list", async () => ({ roots: [{ uri: pathToFileURL(directory).href }] }))
   return client
 }
 
@@ -190,7 +198,11 @@ export interface Interface {
     mcpName: string,
     onAuthorization?: (authorizationUrl: string) => void,
   ) => Effect.Effect<Status, NotFoundError>
-  readonly finishAuth: (mcpName: string, authorizationCode: string) => Effect.Effect<Status, NotFoundError>
+  readonly finishAuth: (
+    mcpName: string,
+    authorizationCode: string,
+    iss?: string,
+  ) => Effect.Effect<Status, NotFoundError>
   readonly removeAuth: (mcpName: string) => Effect.Effect<void>
   readonly supportsOAuth: (mcpName: string) => Effect.Effect<boolean, NotFoundError>
   readonly hasStoredTokens: (mcpName: string) => Effect.Effect<boolean>
@@ -291,11 +303,18 @@ const layer = Layer.effect(
           Effect.map((client) => ({ client, transportName: name })),
           Effect.catch((error) => {
             const lastError = error instanceof Error ? error : new Error(String(error))
+            const registrationRejected =
+              error instanceof RegistrationRejectedError ||
+              lastError.message.includes("registration") ||
+              lastError.message.includes("client_id")
             const isAuthError =
-              error instanceof UnauthorizedError || (authProvider && lastError.message.includes("OAuth"))
+              error instanceof UnauthorizedError ||
+              registrationRejected ||
+              (authProvider && error instanceof SdkHttpError && error.status === 401) ||
+              (authProvider && lastError.message.includes("OAuth"))
 
             if (isAuthError) {
-              if (lastError.message.includes("registration") || lastError.message.includes("client_id")) {
+              if (registrationRejected) {
                 lastStatus = {
                   status: "needs_client_registration" as const,
                   error: "Server does not support dynamic client registration. Please provide clientId in config.",
@@ -454,12 +473,16 @@ const layer = Layer.effect(
         )
       }
 
-      client.setNotificationHandler(LoggingMessageNotificationSchema, (notification) =>
+      client.setNotificationHandler("notifications/message", (notification) =>
         bridge.promise(serverLog(name, notification.params)),
       )
 
       if (!client.getServerCapabilities()?.tools) return
-      client.setNotificationHandler(ToolListChangedNotificationSchema, async () => {
+      client.onToolsChanged = async (error) => {
+        if (error) {
+          await bridge.promise(Effect.logWarning("failed to refresh MCP tools", { server: name, error: error.message }))
+          return
+        }
         if (s.clients[name] !== client || s.status[name]?.status !== "connected") return
 
         const listed = await bridge.promise(McpCatalog.defs(client, timeout))
@@ -468,7 +491,7 @@ const layer = Layer.effect(
 
         s.defs[name] = listed
         await bridge.promise(events.publish(ToolsChanged, { server: name }).pipe(Effect.ignore))
-      })
+      }
     }
 
     function serverLog(name: string, params: LoggingMessageNotification["params"]) {
@@ -904,7 +927,7 @@ const layer = Layer.effect(
         }),
       )
 
-      const code = yield* Effect.promise(() => callbackPromise)
+      const callback = yield* Effect.promise(() => callbackPromise)
 
       const storedState = yield* auth.getOAuthState(mcpName)
       if (storedState !== result.oauthState) {
@@ -912,16 +935,20 @@ const layer = Layer.effect(
         throw new Error("OAuth state mismatch - potential CSRF attack")
       }
       yield* auth.clearOAuthState(mcpName)
-      return yield* finishAuth(mcpName, code)
+      return yield* finishAuth(mcpName, callback.code, callback.iss)
     })
 
-    const finishAuth = Effect.fn("MCP.finishAuth")(function* (mcpName: string, authorizationCode: string) {
+    const finishAuth = Effect.fn("MCP.finishAuth")(function* (
+      mcpName: string,
+      authorizationCode: string,
+      iss?: string,
+    ) {
       yield* requireMcpConfig(mcpName)
       const pending = pendingOAuthTransports.get(mcpName)
       if (!pending) throw new Error(`No pending OAuth flow for MCP server: ${mcpName}`)
 
       const error = yield* Effect.tryPromise({
-        try: () => pending.transport.finishAuth(authorizationCode),
+        try: () => pending.transport.finishAuth(authorizationCode, iss),
         catch: (error) => error,
       }).pipe(
         Effect.match({

packages/opencode/src/mcp/oauth-callback.ts

@@ -9,8 +9,13 @@ const OAUTH_CALLBACK_HOST = "127.0.0.1"
 let currentPort = OAUTH_CALLBACK_PORT
 let currentPath = OAUTH_CALLBACK_PATH
 
+export interface AuthorizationCallback {
+  code: string
+  iss?: string
+}
+
 interface PendingAuth {
-  resolve: (code: string) => void
+  resolve: (callback: AuthorizationCallback) => void
   reject: (error: Error) => void
   timeout: ReturnType<typeof setTimeout>
 }
@@ -49,6 +54,7 @@ function handleRequest(req: import("http").IncomingMessage, res: import("http").
   }
 
   const code = url.searchParams.get("code")
+  const iss = url.searchParams.get("iss") ?? undefined
   const state = url.searchParams.get("state")
   const error = url.searchParams.get("error")
   const errorDescription = url.searchParams.get("error_description")
@@ -95,7 +101,7 @@ function handleRequest(req: import("http").IncomingMessage, res: import("http").
   clearTimeout(pending.timeout)
   pendingAuths.delete(state)
   cleanupStateIndex(state)
-  pending.resolve(code)
+  pending.resolve({ code, iss })
 
   res.writeHead(200, { "Content-Type": "text/html; charset=utf-8" })
   res.end(OauthCallbackPage.success({ provider: "MCP" }))
@@ -130,7 +136,7 @@ export async function ensureRunning(redirectUri?: string): Promise<void> {
   })
 }
 
-export function waitForCallback(oauthState: string, mcpName?: string): Promise<string> {
+export function waitForCallback(oauthState: string, mcpName?: string): Promise<AuthorizationCallback> {
   if (mcpName) mcpNameToState.set(mcpName, oauthState)
   return new Promise((resolve, reject) => {
     const timeout = setTimeout(() => {

packages/opencode/src/mcp/oauth-provider.ts

@@ -1,10 +1,9 @@
-import type { OAuthClientProvider } from "@modelcontextprotocol/sdk/client/auth.js"
 import type {
+  OAuthClientProvider,
   OAuthClientMetadata,
-  OAuthTokens,
-  OAuthClientInformation,
-  OAuthClientInformationFull,
-} from "@modelcontextprotocol/sdk/shared/auth.js"
+  StoredOAuthTokens,
+  StoredOAuthClientInformation,
+} from "@modelcontextprotocol/client"
 import { Effect } from "effect"
 import { McpAuth } from "./auth"
 
@@ -23,6 +22,14 @@ export interface McpOAuthCallbacks {
   onRedirect: (url: URL) => void | Promise<void>
 }
 
+function registrationMetadata(info: StoredOAuthClientInformation) {
+  return {
+    clientIdIssuedAt: "client_id_issued_at" in info ? info.client_id_issued_at : undefined,
+    clientSecretExpiresAt: "client_secret_expires_at" in info ? info.client_secret_expires_at : undefined,
+    redirectUris: "redirect_uris" in info ? info.redirect_uris : undefined,
+  }
+}
+
 export class McpOAuthProvider implements OAuthClientProvider {
   constructor(
     protected mcpName: string,
@@ -52,18 +59,21 @@ export class McpOAuthProvider implements OAuthClientProvider {
     }
   }
 
-  async clientInformation(): Promise<OAuthClientInformation | undefined> {
+  async clientInformation(): Promise<StoredOAuthClientInformation | undefined> {
+    const entry = await Effect.runPromise(this.auth.getForUrl(this.mcpName, this.serverUrl))
     if (this.config.clientId) {
+      const issuer = entry?.clientInfo?.clientId === this.config.clientId ? entry.clientInfo.issuer : undefined
       return {
         client_id: this.config.clientId,
         client_secret: this.config.clientSecret,
+        ...(issuer !== undefined ? { issuer } : {}),
       }
     }
 
     // Check stored client info (from dynamic registration)
     // Use getForUrl to validate credentials are for the current server URL
-    const entry = await Effect.runPromise(this.auth.getForUrl(this.mcpName, this.serverUrl))
     if (entry?.clientInfo) {
+      if (entry.clientInfo.configPreRegistered) return undefined
       // Check if client secret has expired
       if (entry.clientInfo.clientSecretExpiresAt && entry.clientInfo.clientSecretExpiresAt < Date.now() / 1000) {
         return undefined
@@ -71,6 +81,14 @@ export class McpOAuthProvider implements OAuthClientProvider {
       return {
         client_id: entry.clientInfo.clientId,
         client_secret: entry.clientInfo.clientSecret,
+        ...(entry.clientInfo.clientIdIssuedAt !== undefined
+          ? { client_id_issued_at: entry.clientInfo.clientIdIssuedAt }
+          : {}),
+        ...(entry.clientInfo.clientSecretExpiresAt !== undefined
+          ? { client_secret_expires_at: entry.clientInfo.clientSecretExpiresAt }
+          : {}),
+        redirect_uris: entry.clientInfo.redirectUris ? [...entry.clientInfo.redirectUris] : [this.redirectUrl],
+        ...(entry.clientInfo.issuer !== undefined ? { issuer: entry.clientInfo.issuer } : {}),
       }
     }
 
@@ -78,22 +96,36 @@ export class McpOAuthProvider implements OAuthClientProvider {
     return undefined
   }
 
-  async saveClientInformation(info: OAuthClientInformationFull): Promise<void> {
+  async saveClientInformation(info: StoredOAuthClientInformation): Promise<void> {
+    if (this.config.clientId && info.client_id === this.config.clientId) {
+      await Effect.runPromise(
+        this.auth.updateClientInfo(
+          this.mcpName,
+          { clientId: info.client_id, issuer: info.issuer, configPreRegistered: true },
+          this.serverUrl,
+        ),
+      )
+      return
+    }
+
+    const metadata = registrationMetadata(info)
     await Effect.runPromise(
       this.auth.updateClientInfo(
         this.mcpName,
         {
           clientId: info.client_id,
           clientSecret: info.client_secret,
-          clientIdIssuedAt: info.client_id_issued_at,
-          clientSecretExpiresAt: info.client_secret_expires_at,
+          clientIdIssuedAt: metadata.clientIdIssuedAt,
+          clientSecretExpiresAt: metadata.clientSecretExpiresAt,
+          redirectUris: metadata.redirectUris ? [...metadata.redirectUris] : [this.redirectUrl],
+          issuer: info.issuer,
         },
         this.serverUrl,
       ),
     )
   }
 
-  async tokens(): Promise<OAuthTokens | undefined> {
+  async tokens(): Promise<StoredOAuthTokens | undefined> {
     // Use getForUrl to validate tokens are for the current server URL
     const entry = await Effect.runPromise(this.auth.getForUrl(this.mcpName, this.serverUrl))
     if (!entry?.tokens) return undefined
@@ -106,18 +138,20 @@ export class McpOAuthProvider implements OAuthClientProvider {
         ? Math.max(0, Math.floor(entry.tokens.expiresAt - Date.now() / 1000))
         : undefined,
       scope: entry.tokens.scope,
+      issuer: entry.tokens.issuer,
     }
   }
 
-  async saveTokens(tokens: OAuthTokens): Promise<void> {
+  async saveTokens(tokens: StoredOAuthTokens): Promise<void> {
     await Effect.runPromise(
       this.auth.updateTokens(
         this.mcpName,
         {
           accessToken: tokens.access_token,
           refreshToken: tokens.refresh_token,
-          expiresAt: tokens.expires_in ? Date.now() / 1000 + tokens.expires_in : undefined,
+          expiresAt: tokens.expires_in !== undefined ? Date.now() / 1000 + tokens.expires_in : undefined,
           scope: tokens.scope,
+          issuer: tokens.issuer,
         },
         this.serverUrl,
       ),
@@ -181,10 +215,10 @@ export class McpOAuthProvider implements OAuthClientProvider {
 }
 
 export class McpOAuthPendingProvider extends McpOAuthProvider {
-  private pendingClientInfo?: OAuthClientInformationFull
-  private pendingTokens?: OAuthTokens
+  private pendingClientInfo?: StoredOAuthClientInformation
+  private pendingTokens?: StoredOAuthTokens
 
-  override async clientInformation(): Promise<OAuthClientInformation | undefined> {
+  override async clientInformation(): Promise<StoredOAuthClientInformation | undefined> {
     if (!this.config.clientId) return this.pendingClientInfo
     return {
       client_id: this.config.clientId,
@@ -192,15 +226,15 @@ export class McpOAuthPendingProvider extends McpOAuthProvider {
     }
   }
 
-  override async saveClientInformation(info: OAuthClientInformationFull): Promise<void> {
+  override async saveClientInformation(info: StoredOAuthClientInformation): Promise<void> {
     this.pendingClientInfo = info
   }
 
-  override async tokens(): Promise<OAuthTokens | undefined> {
+  override async tokens(): Promise<StoredOAuthTokens | undefined> {
     return this.pendingTokens
   }
 
-  override async saveTokens(tokens: OAuthTokens): Promise<void> {
+  override async saveTokens(tokens: StoredOAuthTokens): Promise<void> {
     this.pendingTokens = tokens
   }
 
@@ -211,6 +245,7 @@ export class McpOAuthPendingProvider extends McpOAuthProvider {
 
   async commit(): Promise<void> {
     if (!this.pendingTokens) return
+    const pendingMetadata = this.pendingClientInfo ? registrationMetadata(this.pendingClientInfo) : undefined
     await Effect.runPromise(
       this.auth.set(
         this.mcpName,
@@ -218,16 +253,22 @@ export class McpOAuthPendingProvider extends McpOAuthProvider {
           tokens: {
             accessToken: this.pendingTokens.access_token,
             refreshToken: this.pendingTokens.refresh_token,
-            expiresAt: this.pendingTokens.expires_in ? Date.now() / 1000 + this.pendingTokens.expires_in : undefined,
+            expiresAt:
+              this.pendingTokens.expires_in !== undefined
+                ? Date.now() / 1000 + this.pendingTokens.expires_in
+                : undefined,
             scope: this.pendingTokens.scope,
+            issuer: this.pendingTokens.issuer,
           },
           clientInfo:
             this.pendingClientInfo && !this.config.clientId
               ? {
                   clientId: this.pendingClientInfo.client_id,
                   clientSecret: this.pendingClientInfo.client_secret,
-                  clientIdIssuedAt: this.pendingClientInfo.client_id_issued_at,
-                  clientSecretExpiresAt: this.pendingClientInfo.client_secret_expires_at,
+                  clientIdIssuedAt: pendingMetadata?.clientIdIssuedAt,
+                  clientSecretExpiresAt: pendingMetadata?.clientSecretExpiresAt,
+                  redirectUris: pendingMetadata?.redirectUris ? [...pendingMetadata.redirectUris] : [this.redirectUrl],
+                  issuer: this.pendingClientInfo.issuer,
                 }
               : undefined,
         },

packages/opencode/src/server/routes/instance/httpapi/groups/mcp.ts

@@ -20,6 +20,7 @@ export const AuthStartResponse = Schema.Struct({
 })
 export const AuthCallbackPayload = Schema.Struct({
   code: Schema.String,
+  iss: Schema.optional(Schema.String),
 })
 export const AuthRemoveResponse = Schema.Struct({
   success: Schema.Literal(true),

packages/opencode/src/server/routes/instance/httpapi/handlers/mcp.ts

@@ -38,7 +38,7 @@ export const mcpHandlers = HttpApiBuilder.group(InstanceHttpApi, "mcp", (handler
       payload: typeof AuthCallbackPayload.Type
     }) {
       return yield* mcp
-        .finishAuth(ctx.params.name, ctx.payload.code)
+        .finishAuth(ctx.params.name, ctx.payload.code, ctx.payload.iss)
         .pipe(
           Effect.catchTag("MCP.NotFoundError", (error) =>
             Effect.fail(

packages/opencode/src/tool/code-mode.ts

@@ -1,5 +1,5 @@
 import * as Tool from "./tool"
-import { CallToolResultSchema, type CallToolResult } from "@modelcontextprotocol/sdk/types.js"
+import { type CallToolResult } from "@modelcontextprotocol/client"
 import { Cause, Effect, Schema } from "effect"
 import { CodeMode, Tool as SandboxTool, toolError } from "@opencode-ai/codemode"
 import { MCP } from "@/mcp"
@@ -149,7 +149,6 @@ const invokeChildTool = Effect.fn("CodeMode.invokeChildTool")(function* (input:
     return yield* Effect.promise(async () => {
       const raw = await input.entry.tool.client.callTool(
         { name: input.entry.tool.def.name, arguments: input.args },
-        CallToolResultSchema,
         {
           resetTimeoutOnProgress: true,
           signal: input.ctx.abort,