diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index 2879f7edafc..6833cd0c0c8 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -1,5 +1,6 @@
 import type { APICallError, ModelMessage } from "ai"
 import { mergeDeep, unique } from "remeda"
+import type { JSONSchema7 } from "@ai-sdk/provider"
 import type { JSONSchema } from "zod/v4/core"
 import type { Provider } from "./provider"
 import type { ModelsDev } from "./models"
@@ -719,7 +720,7 @@ export namespace ProviderTransform {
     return standardLimit
   }
 
-  export function schema(model: Provider.Model, schema: JSONSchema.BaseSchema) {
+  export function schema(model: Provider.Model, schema: JSONSchema.BaseSchema | JSONSchema7): JSONSchema7 {
     /*
     if (["openai", "azure"].includes(providerID)) {
       if (schema.type === "object" && schema.properties) {
@@ -793,7 +794,7 @@ export namespace ProviderTransform {
       schema = sanitizeGemini(schema)
     }
 
-    return schema
+    return schema as JSONSchema7
   }
 
   export function error(providerID: string, error: APICallError) {
diff --git a/packages/opencode/src/session/prompt.ts b/packages/opencode/src/session/prompt.ts
index e0861c4df52..b85a7c336e9 100644
--- a/packages/opencode/src/session/prompt.ts
+++ b/packages/opencode/src/session/prompt.ts
@@ -9,7 +9,7 @@ import { SessionRevert } from "./revert"
 import { Session } from "."
 import { Agent } from "../agent/agent"
 import { Provider } from "../provider/provider"
-import { type Tool as AITool, tool, jsonSchema, type ToolCallOptions } from "ai"
+import { type Tool as AITool, tool, jsonSchema, type ToolCallOptions, asSchema } from "ai"
 import { SessionCompaction } from "./compaction"
 import { Instance } from "../project/instance"
 import { Bus } from "../bus"
@@ -738,6 +738,8 @@ export namespace SessionPrompt {
       const execute = item.execute
       if (!execute) continue
 
+      const transformed = ProviderTransform.schema(input.model, asSchema(item.inputSchema).jsonSchema)
+      item.inputSchema = jsonSchema(transformed)
       // Wrap execute to add plugin hooks and format output
       item.execute = async (args, opts) => {
         const ctx = context(args, opts)