MAX_MCP_OUTPUT_TOKENS

Updated October 13, 2026 by Alex Sorokoletov

MAX_MCP_OUTPUT_TOKENS is a Claude Code environment variable: Max tokens for MCP tool output. Its release history is not tracked here. It is listed in the official reference.

Status	Present in v2.1.294
Category	Authentication
Official docs	Listed

How to set it

For one session, export it in the shell that starts Claude Code:

export MAX_MCP_OUTPUT_TOKENS=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "MAX_MCP_OUTPUT_TOKENS": "<value>"
  }
}

Related variables

CLAUDE_CODE_FILE_READ_MAX_OUTPUT_TOKENS: Max tokens for file read output.
CLAUDE_CODE_MAX_OUTPUT_TOKENS: Maximum output tokens; validated per-model.
CLAUDE_CODE_MAX_CONTEXT_TOKENS: Sets an explicit ceiling on the context window size used during a session.
MAX_THINKING_TOKENS: Likely controlled via API settings now.
CLAUDE_CODE_IDLE_COMPACT_MIN_TOKENS: Sets the minimum conversation size, in tokens, before idle compaction runs.
MCP_OAUTH_CALLBACK_PORT: OAuth callback server port.
CLAUDE_BG_SOCKET_TOKENS_PATH
CLAUDE_CODE_MCP_SERVE_AUTH_TOKEN

Frequently asked questions

What does MAX_MCP_OUTPUT_TOKENS do?

Max tokens for MCP tool output

Which Claude Code version has MAX_MCP_OUTPUT_TOKENS?

Its release history is not tracked here.

How do I set MAX_MCP_OUTPUT_TOKENS?

Export it before starting Claude Code (export MAX_MCP_OUTPUT_TOKENS=value), or add it to the "env" object in ~/.claude/settings.json to apply it to every session.

All variables, searchable: Claude Code environment variables.