diff --git a/packages/ai/src/providers/google-shared.ts b/packages/ai/src/providers/google-shared.ts
index 57b592382..2f0696cea 100644
--- a/packages/ai/src/providers/google-shared.ts
+++ b/packages/ai/src/providers/google-shared.ts
@@ -239,6 +239,33 @@ export function convertMessages<T extends GoogleApiType>(model: Model<T>, contex
 	return contents;
 }
 
+const JSON_SCHEMA_META_DECLARATIONS = new Set([
+	"$schema",
+	"$id",
+	"$anchor",
+	"$dynamicAnchor",
+	"$vocabulary",
+	"$comment",
+	"$defs",
+	"definitions", // pre-draft-2019-09 equivalent of $defs
+]);
+
+/**
+ * Strip meta-declarations from a schema obj
+ */
+function sanitizeForOpenApi(schema: unknown): unknown {
+	if (typeof schema !== "object" || schema === null || Array.isArray(schema)) {
+		return schema;
+	}
+
+	const result: Record<string, unknown> = {};
+	for (const [key, value] of Object.entries(schema)) {
+		if (JSON_SCHEMA_META_DECLARATIONS.has(key)) continue;
+		result[key] = sanitizeForOpenApi(value);
+	}
+	return result;
+}
+
 /**
  * Convert tools to Gemini function declarations format.
  *
@@ -257,7 +284,9 @@ export function convertTools(
 			functionDeclarations: tools.map((tool) => ({
 				name: tool.name,
 				description: tool.description,
-				...(useParameters ? { parameters: tool.parameters } : { parametersJsonSchema: tool.parameters }),
+				...(useParameters
+					? { parameters: sanitizeForOpenApi(tool.parameters as unknown) }
+					: { parametersJsonSchema: tool.parameters }),
 			})),
 		},
 	];
diff --git a/packages/ai/test/google-shared-convert-tools.test.ts b/packages/ai/test/google-shared-convert-tools.test.ts
new file mode 100644
index 000000000..6cce3175e
--- /dev/null
+++ b/packages/ai/test/google-shared-convert-tools.test.ts
@@ -0,0 +1,187 @@
+import { describe, expect, it } from "vitest";
+import { convertTools } from "../src/providers/google-shared.js";
+import type { Tool } from "../src/types.js";
+
+function makeTool(parameters: Record<string, unknown>): Tool {
+	return {
+		name: "test_tool",
+		description: "A test tool",
+		parameters: parameters as Tool["parameters"],
+	};
+}
+
+describe("google-shared convertTools", () => {
+	it("strips JSON Schema meta keys from parameters when useParameters=true", () => {
+		const tools = [
+			makeTool({
+				$schema: "http://json-schema.org/draft-07/schema#",
+				$id: "urn:bash-tool",
+				$comment: "A bash tool for demonstration",
+				$defs: {
+					commandDef: { type: "string" },
+				},
+				definitions: {
+					legacyDef: { type: "number" },
+				},
+				type: "object",
+				properties: {
+					command: { type: "string" },
+				},
+				required: ["command"],
+			}),
+		];
+
+		const result = convertTools(tools, true);
+		const decl = result?.[0]?.functionDeclarations?.[0];
+
+		expect(decl).toBeDefined();
+		expect(decl?.parameters).toEqual({
+			type: "object",
+			properties: {
+				command: { type: "string" },
+			},
+			required: ["command"],
+		});
+		expect(decl?.parameters).not.toHaveProperty("$schema");
+		expect(decl?.parameters).not.toHaveProperty("$id");
+		expect(decl?.parameters).not.toHaveProperty("$comment");
+		expect(decl?.parameters).not.toHaveProperty("$defs");
+		expect(decl?.parameters).not.toHaveProperty("definitions");
+	});
+
+	it("recursively strips nested JSON Schema meta keys", () => {
+		const tools = [
+			makeTool({
+				$schema: "http://json-schema.org/draft-07/schema#",
+				type: "object",
+				properties: {
+					deep: {
+						$schema: "http://json-schema.org/draft-07/schema#",
+						$id: "urn:nested",
+						type: "string",
+					},
+				},
+			}),
+		];
+
+		const result = convertTools(tools, true);
+		const decl = result?.[0]?.functionDeclarations?.[0];
+
+		expect(decl).toBeDefined();
+		expect(decl?.parameters).toEqual({
+			type: "object",
+			properties: {
+				deep: {
+					type: "string",
+				},
+			},
+		});
+	});
+
+	it("preserves $ref while stripping meta keys", () => {
+		const tools = [
+			makeTool({
+				$schema: "http://json-schema.org/draft-07/schema#",
+				type: "object",
+				properties: {
+					refProp: {
+						$ref: "#/$defs/someDef",
+						type: "string",
+					},
+				},
+			}),
+		];
+
+		const result = convertTools(tools, true);
+		const decl = result?.[0]?.functionDeclarations?.[0];
+
+		expect(decl).toBeDefined();
+		expect(decl?.parameters).toEqual({
+			type: "object",
+			properties: {
+				refProp: {
+					$ref: "#/$defs/someDef",
+					type: "string",
+				},
+			},
+		});
+	});
+
+	it("does not mutate the original Tool.parameters object", () => {
+		const originalParameters = {
+			$schema: "http://json-schema.org/draft-07/schema#",
+			type: "object",
+			properties: {
+				command: { type: "string" },
+			},
+			required: ["command"],
+		};
+		const tools = [makeTool(originalParameters)];
+
+		convertTools(tools, true);
+
+		expect(originalParameters).toEqual({
+			$schema: "http://json-schema.org/draft-07/schema#",
+			type: "object",
+			properties: {
+				command: { type: "string" },
+			},
+			required: ["command"],
+		});
+	});
+
+	it("preserves $schema in parametersJsonSchema when useParameters=false", () => {
+		const tools = [
+			makeTool({
+				$schema: "http://json-schema.org/draft-07/schema#",
+				type: "object",
+				properties: {
+					command: { type: "string" },
+				},
+				required: ["command"],
+			}),
+		];
+
+		const result = convertTools(tools, false);
+		const decl = result?.[0]?.functionDeclarations?.[0];
+
+		expect(decl).toBeDefined();
+		expect(decl?.parametersJsonSchema).toEqual({
+			$schema: "http://json-schema.org/draft-07/schema#",
+			type: "object",
+			properties: {
+				command: { type: "string" },
+			},
+			required: ["command"],
+		});
+	});
+
+	it("handles tools without $schema gracefully", () => {
+		const tools = [
+			makeTool({
+				type: "object",
+				properties: {
+					path: { type: "string" },
+				},
+				required: ["path"],
+			}),
+		];
+
+		const result = convertTools(tools, true);
+		const decl = result?.[0]?.functionDeclarations?.[0];
+
+		expect(decl).toBeDefined();
+		expect(decl?.parameters).toEqual({
+			type: "object",
+			properties: {
+				path: { type: "string" },
+			},
+			required: ["path"],
+		});
+	});
+
+	it("returns undefined for empty tool list", () => {
+		expect(convertTools([])).toBeUndefined();
+		expect(convertTools([], true)).toBeUndefined();
+	});
+});