diff --git a/bun.lock b/bun.lock
index ce00c1142dc0..363e99b69b2c 100644
--- a/bun.lock
+++ b/bun.lock
@@ -353,6 +353,7 @@
         "@ff-labs/fff-node": "0.10.5",
         "@lydell/node-pty": "catalog:",
         "@modelcontextprotocol/client": "2.0.0",
+        "@modelcontextprotocol/core": "2.0.0",
         "@opencode-ai/pty": "0.1.13",
         "@opencode/ai": "workspace:*",
         "@opencode/codemode": "workspace:*",
diff --git a/packages/client/src/promise/generated/types.ts b/packages/client/src/promise/generated/types.ts
index 763389848eb1..ac7a2d92e39e 100644
--- a/packages/client/src/promise/generated/types.ts
+++ b/packages/client/src/promise/generated/types.ts
@@ -2012,6 +2012,7 @@ export type ConfigEntry =
                         scope?: string
                         callback_port?: number
                         redirect_uri?: string
+                        auth_server_metadata_url?: string
                       }
                     | false
                   disabled?: boolean
@@ -4667,6 +4668,7 @@ export type McpAddInput = {
                 readonly scope?: string
                 readonly callback_port?: number
                 readonly redirect_uri?: string
+                readonly auth_server_metadata_url?: string
               }
             | false
           readonly disabled?: boolean
diff --git a/packages/core/package.json b/packages/core/package.json
index 218979b4d87c..82965f8dd303 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -111,6 +111,7 @@
     "@ff-labs/fff-node": "0.10.5",
     "@lydell/node-pty": "catalog:",
     "@modelcontextprotocol/client": "2.0.0",
+    "@modelcontextprotocol/core": "2.0.0",
     "@opencode-ai/pty": "0.1.13",
     "@opencode/ai": "workspace:*",
     "@opencode/codemode": "workspace:*",
diff --git a/packages/core/src/mcp/oauth.ts b/packages/core/src/mcp/oauth.ts
index a72a1a500a52..fc8616bd6e52 100644
--- a/packages/core/src/mcp/oauth.ts
+++ b/packages/core/src/mcp/oauth.ts
@@ -7,6 +7,7 @@ import {
   discoverOAuthServerInfo,
   extractWWWAuthenticateParams,
   parseErrorResponse,
+  resourceUrlFromServerUrl,
   UnauthorizedError,
   type FetchLike,
   type OAuthClientProvider,
@@ -14,6 +15,7 @@ import {
   type StoredOAuthClientInformation,
   type StoredOAuthTokens,
 } from "@modelcontextprotocol/client"
+import { OAuthMetadataSchema, OpenIdProviderDiscoveryMetadataSchema } from "@modelcontextprotocol/core"
 import { Cause, Deferred, Effect } from "effect"
 import { ConfigMCP } from "@opencode/schema/config/mcp"
 import { Credential } from "../credential.js"
@@ -99,6 +101,25 @@ export const loggedFetch = (fields: { readonly server: string; readonly director
     return request
   })
 
+// A configured authorization server document stands in for RFC 9728 discovery: the SDK reuses this
+// state instead of probing the resource server, whose well-known path may not exist.
+export const configuredDiscovery = async (input: {
+  readonly config: typeof ConfigMCP.Remote.Type
+  readonly fetchFn: FetchLike
+}): Promise<OAuthDiscoveryState | undefined> => {
+  const url = input.config.oauth ? input.config.oauth.auth_server_metadata_url : undefined
+  if (!url) return undefined
+  const response = await input.fetchFn(url, { headers: { accept: "application/json" } })
+  if (!response.ok) throw new Error(`HTTP ${response.status} trying to load OAuth authorization server metadata`)
+  const body = await response.json()
+  const metadata = OAuthMetadataSchema.safeParse(body).data ?? OpenIdProviderDiscoveryMetadataSchema.parse(body)
+  return {
+    authorizationServerUrl: metadata.issuer,
+    authorizationServerMetadata: metadata,
+    resourceMetadata: { resource: resourceUrlFromServerUrl(input.config.url).toString() },
+  }
+}
+
 export interface Store {
   readonly tokens: () => Promise<StoredOAuthTokens | undefined>
   readonly saveTokens: (tokens: StoredOAuthTokens) => Promise<void>
@@ -134,7 +155,10 @@ export const provider = (options: Options): OAuthClientProvider => {
   let discovery: OAuthDiscoveryState | undefined = options.discovery
   return {
     redirectUrl,
-    discoveryState: () => discovery,
+    discoveryState: async () => {
+      discovery ??= await configuredDiscovery({ config: options.config, fetchFn: send })
+      return discovery
+    },
     saveDiscoveryState: (state) => {
       discovery = state
     },
@@ -388,7 +412,9 @@ export const authorize = (input: {
     // CIMD needs the server to advertise it and accept public clients, and our published document only
     // lists the loopback redirect; a configured client_id always wins.
     const discovery = yield* Effect.tryPromise({
-      try: () => discoverOAuthServerInfo(input.config.url, { resourceMetadataUrl, fetchFn }),
+      try: async () =>
+        (await configuredDiscovery({ config: input.config, fetchFn })) ??
+        discoverOAuthServerInfo(input.config.url, { resourceMetadataUrl, fetchFn }),
       catch: (error) => (error instanceof Error ? error : new Error(String(error))),
     })
     const cimd =
diff --git a/packages/core/test/mcp-oauth.test.ts b/packages/core/test/mcp-oauth.test.ts
index e5994e255055..bc169813d8ae 100644
--- a/packages/core/test/mcp-oauth.test.ts
+++ b/packages/core/test/mcp-oauth.test.ts
@@ -352,6 +352,38 @@ describe("MCP OAuth", () => {
     expect(url.pathname).toBe("/as/authorize")
   })
 
+  test("uses configured authorization server metadata when the resource publishes none", async () => {
+    const { server: issuer } = authorizationServer({})
+    const resource = Bun.serve({ port: 0, fetch: () => new Response(null, { status: 404 }) })
+    const url = `${resource.url.origin}/mcp`
+    const oauth = {
+      client_id: "client",
+      auth_server_metadata_url: `${issuer.url.origin}/.well-known/oauth-authorization-server`,
+    }
+
+    const { url: authorization } = await Effect.runPromise(Effect.scoped(start(url, oauth)))
+    expect(authorization.origin).toBe(issuer.url.origin)
+    expect(authorization.pathname).toBe("/authorize")
+    expect(authorization.searchParams.get("resource")).toBe(url)
+
+    const { server, tokenRequests } = authorizationServer({})
+    const store = memoryCredentials([credential({ access: "expired", refresh: "refresh", url })])
+    const oauthProvider = await connectProvider(
+      new ConfigMCP.Remote({
+        type: "remote",
+        url,
+        oauth: { ...oauth, auth_server_metadata_url: `${server.url.origin}/.well-known/oauth-authorization-server` },
+      }),
+      store,
+    )
+    await auth(oauthProvider, { serverUrl: url }).finally(() => {
+      resource.stop(true)
+      issuer.stop(true)
+      server.stop(true)
+    })
+    expect(tokenRequests[0]?.get("grant_type")).toBe("refresh_token")
+  })
+
   test("forwards iss from the redirect so issuer-advertising servers can complete", async () => {
     const { server } = authorizationServer({ authorization_response_iss_parameter_supported: true })
     const result = await Effect.runPromise(
diff --git a/packages/protocol/openapi.json b/packages/protocol/openapi.json
index 4a37b3644f0f..f9c08e4bb080 100644
--- a/packages/protocol/openapi.json
+++ b/packages/protocol/openapi.json
@@ -15250,6 +15250,9 @@
           },
           "redirect_uri": {
             "type": "string"
+          },
+          "auth_server_metadata_url": {
+            "type": "string"
           }
         },
         "additionalProperties": false
@@ -15549,6 +15552,9 @@
           },
           "requireAssistantAfterTool": {
             "type": "boolean"
+          },
+          "supportsPromptCacheKey": {
+            "type": "boolean"
           }
         },
         "additionalProperties": false
diff --git a/packages/schema/src/mcp.ts b/packages/schema/src/mcp.ts
index bf8c20a57c04..ffcab1c4c944 100644
--- a/packages/schema/src/mcp.ts
+++ b/packages/schema/src/mcp.ts
@@ -44,6 +44,10 @@ export class OAuthConfig extends Schema.Class<OAuthConfig>("Mcp.OAuthConfig")({
   scope: Schema.String.pipe(optional),
   callback_port: Schema.Int.check(Schema.isBetween({ minimum: 1, maximum: 65535 })).pipe(optional),
   redirect_uri: Schema.String.pipe(optional),
+  auth_server_metadata_url: Schema.String.pipe(optional).annotate({
+    description:
+      "URL of the OAuth or OpenID Connect authorization server metadata document. Set when the MCP server does not publish protected resource metadata that names its authorization server.",
+  }),
 }) {}
 
 export class RemoteConfig extends Schema.Class<RemoteConfig>("Mcp.RemoteConfig")({
diff --git a/services/www/openapi.json b/services/www/openapi.json
index 4a37b3644f0f..f9c08e4bb080 100644
--- a/services/www/openapi.json
+++ b/services/www/openapi.json
@@ -15250,6 +15250,9 @@
           },
           "redirect_uri": {
             "type": "string"
+          },
+          "auth_server_metadata_url": {
+            "type": "string"
           }
         },
         "additionalProperties": false
@@ -15549,6 +15552,9 @@
           },
           "requireAssistantAfterTool": {
             "type": "boolean"
+          },
+          "supportsPromptCacheKey": {
+            "type": "boolean"
           }
         },
         "additionalProperties": false
diff --git a/services/www/public/openapi.json b/services/www/public/openapi.json
index 4a37b3644f0f..f9c08e4bb080 100644
--- a/services/www/public/openapi.json
+++ b/services/www/public/openapi.json
@@ -15250,6 +15250,9 @@
           },
           "redirect_uri": {
             "type": "string"
+          },
+          "auth_server_metadata_url": {
+            "type": "string"
           }
         },
         "additionalProperties": false
@@ -15549,6 +15552,9 @@
           },
           "requireAssistantAfterTool": {
             "type": "boolean"
+          },
+          "supportsPromptCacheKey": {
+            "type": "boolean"
           }
         },
         "additionalProperties": false
diff --git a/services/www/src/docs/content/mcp-servers.mdx b/services/www/src/docs/content/mcp-servers.mdx
index 6a87e1c4678a..6c0d9b13adbc 100644
--- a/services/www/src/docs/content/mcp-servers.mdx
+++ b/services/www/src/docs/content/mcp-servers.mdx
@@ -230,6 +230,7 @@ When a provider gives you client credentials, use V2's snake_case OAuth fields:
 | `scope` | Space-delimited scopes to request. |
 | `callback_port` | Local callback port from `1` through `65535`. An available ephemeral port is the default. |
 | `redirect_uri` | Pre-registered loopback URI whose path and port reach the local callback listener. |
+| `auth_server_metadata_url` | URL of the authorization server's OAuth or OpenID Connect metadata document. Set it when the MCP server does not publish protected resource metadata that names its authorization server. |
 
 Remove stored OAuth credentials when you need to sign in again or switch accounts: