Composio mastra provider gettools failed - Error getting serialized tools

TL;DR

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.

Steps

1. 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.

When to use

You are seeing this: 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. Use this skill when you run into "Composio mastra provider gettools failed - Error getting serialized tools".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

Versions mentioned in the source: composiocore 0.2.2. If you are on something much newer or older, the details may have shifted.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

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