---
description: Error handling conventions using neverthrow
---
# Error Handling
Use neverthrow for explicit error handling. Never throw exceptions for expected errors.
## Pattern
```typescript
import { ok, err, Result } from "neverthrow";
type MyError = {
code: "INVALID_INPUT" | "NOT_FOUND";
message: string;
};
function process(input: string): Result<Output, MyError> {
if (!input) {
return err({ code: "INVALID_INPUT", message: "Input required" });
}
return ok(processedValue);
}
```
## Usage in MCP Tools
```typescript
handler: async ({ input }) => {
const result = processFeature(input);
if (result.isErr()) {
return {
isError: true,
content: [{ type: "text", text: result.error.message }],
};
}
return {
content: [{ type: "text", text: formatOutput(result.value) }],
};
}
```
