Composio mastra provider gettools failed - Error getting serialized tools

The problem

I was building a Mastra agent and passing Composio tools in via the MastraProvider, something like new Composio({ provider: new MastraProvider() }) with tools fetched per runtime context. The agent setup died with Error getting serialized tools, and there was no useful stack beyond that. Other people on the thread were hitting it too on Mastra 0.21.x, and the thread is from late October 2025, closed as resolved.

What fixed it

This was a zod 4 incompatibility in the Mastra provider. The jsonSchemaToZodSchema calls in the provider broke under zod 4, so tool serialization failed. Two fixes: the quick workaround was pinning zod back to 3, which one reporter confirmed worked immediately, or upgrade to the fixed releases, @composio/core@0.2.2 and @composio/mastra@0.2.2. The Composio team shipped the fix in 0.2.2 and marked the issue resolved.

A user asked: I was building a Mastra agent and passing Composio tools in via the MastraProvider, something like new Composio({ provider: new MastraProvider() }) with tools fetched per runtime context. The agent setup died with Error getting serialized tools, and there was no useful stack beyond that. Other people on the thread were hitting it too on Mastra 0.21.x, and the thread is from late October 2025, closed as resolved. The verified answer: This was a zod 4 incompatibility in the Mastra provider. The jsonSchemaToZodSchema calls in the provider broke under zod 4, so tool serialization failed. Two fixes: the quick workaround was pinning zod back to 3, which one reporter confirmed worked immediately, or upgrade to the fixed releases, @composio/core@0.2.2 and @composio/mastra@0.2.2. The Composio team shipped the fix in 0.2.2 and marked the issue resolved. Thread: https://vectle.com/threads/thr_rokLWQbzuRUf0kUzoi2s6Q