> ## Documentation Index
> Fetch the complete documentation index at: https://mcp-use.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

<AgentInstructions>

## Submitting Feedback

If you encounter incorrect, outdated, or confusing documentation on this page, submit feedback:

POST https://mcp-use.com/docs/feedback

```json
{
  "path": "/python/changelog/1_3_11",
  "feedback": "Description of the issue"
}
```

Only submit feedback when you have something specific and actionable to report.

</AgentInstructions>

# Version 1.3.11

> Enhanced error handling, authorization features, and critical bug fixes

export const Contributors = props => {
  let users = [];
  if (props.usernames) {
    users = Array.isArray(props.usernames) ? props.usernames : String(props.usernames).split(",").map(u => u.trim());
  } else if (props.users) {
    users = String(props.users).split(",").map(u => u.trim());
  }
  if (users.length === 0) return null;
  return <div>
      <span className="text-base font-medium text-zinc-600 dark:text-zinc-300">Contributors</span>
      <div className="flex items-center" style={{
    marginTop: '8px'
  }}>
        {users.map((username, index) => <a key={username} href={`https://github.com/${username}`} target="_blank" rel="noopener noreferrer" title={`@${username}`} className="relative rounded-full transition-all duration-200 hover:z-50 hover:scale-110 block" style={{
    marginLeft: index === 0 ? 0 : '-8px',
    zIndex: users.length - index,
    lineHeight: 0
  }}>
            <img noZoom src={`https://github.com/${username}.png`} alt={`@${username}`} width="32" height="32" style={{
    display: 'block',
    margin: 0
  }} className="rounded-full ring-2 ring-zinc-100 dark:ring-zinc-900" />
          </a>)}
      </div>
    </div>;
};

<Card img="https://mcp-use.com/api/og/release?v=1.3.11" title="Release 1.3.11" href="https://github.com/mcp-use/mcp-use/releases/tag/1.3.11">
  This release brings significant improvements to MCP-Use with enhanced error handling, new authorization capabilities, and several critical bug fixes. The most notable additions include a comprehensive authorization system and improved reliability across HTTP connectors and subprocess management.
</Card>

## New Features

### Authorization System

**[PR #149](https://github.com/pietrozullo/mcp-use/pull/149) by @pietrozullo**

A comprehensive OAuth2 and Bearer token authentication framework has been added to MCP-Use, enabling secure access control for MCP servers and clients. The system includes automatic OAuth discovery, dynamic client registration, and secure token storage. Key features include file-based token storage, automatic token refresh, OAuth metadata discovery, and secure callback handling for the authorization code flow.

For detailed usage examples and configuration options, see the [Authentication documentation](/python/client/authentication).

## Bug Fixes & Improvements

### HTTP Connector Error Handling

**[PR #279](https://github.com/pietrozullo/mcp-use/pull/279) by @renvins**

Significantly improved error handling in HTTP connectors with better authentication error detection and graceful fallback between transport methods. The system now properly handles HTTP 401/403/407 errors and provides clearer diagnostic messages when authentication fails.

### Empty Tool Result Handling

**[PR #273](https://github.com/pietrozullo/mcp-use/pull/273) by @renvins**

Fixed a critical issue where empty tool results (`content: []`) were causing validation errors in the LangChain adapter. The system now correctly processes empty results and handles cases where tools legitimately return no content.

### JSON Schema Enum Validation

**[PR #270](https://github.com/pietrozullo/mcp-use/pull/270) by @Amrithesh-Kakkoth**

Resolved a validation issue in `jsonschema_to_pydantic` conversion where enum fields without explicit type declarations were failing validation. The fix automatically adds `"type": "string"` to enum fields, ensuring proper Pydantic model generation.

```python theme={null}
# Before: This would fail validation
{"enum": ["x", "y", "z"]}

# After: Automatically fixed to
{"type": "string", "enum": ["x", "y", "z"]}
```

### Documentation Fix

**[PR #266](https://github.com/pietrozullo/mcp-use/pull/266) by @renvins**

Corrected a typo in the README documentation where `astream` was incorrectly referenced instead of `stream`, improving clarity for developers following the streaming examples.

### MCPAgent Execution Tracking

**[PR #254](https://github.com/pietrozullo/mcp-use/pull/254) by @hetsaraiya**

Enhanced the MCPAgent execution flow with comprehensive success/failure tracking and telemetry collection. The system now properly tracks execution status, steps taken, tools used, and execution time for better observability and debugging.

```python theme={null}
# New telemetry tracking includes:
# - Execution success/failure status
# - Number of steps taken
# - Tools used during execution
# - Response time and error details
# - Agent configuration metadata
```

### Subprocess Cleanup

**[PR #231](https://github.com/pietrozullo/mcp-use/pull/231) by @lorenss-m**

Fixed a critical resource leak in subprocess management when running multiple MCP clients concurrently. The fix ensures proper process termination and cleanup, preventing zombie processes and memory leaks in long-running applications.

## Maintenance

### Automated Dependency Updates

**[PRs #261](https://github.com/pietrozullo/mcp-use/pull/261), [#253](https://github.com/pietrozullo/mcp-use/pull/253), [#248](https://github.com/pietrozullo/mcp-use/pull/248) by @github-actions\[bot]**

Regular automated updates to dependent package information, ensuring the project stays current with its ecosystem and maintains compatibility with the latest versions of dependencies.

## Contributors

Thank you to all contributors who made this release possible:

<Contributors users="pietrozullo,renvins,Amrithesh-Kakkoth,hetsaraiya,lorenss-m" />