// event · cli

Claude Code v2.1.280 adds Claude Opus 5.5 as default Opus model with 1M context

cli

vendor: anthropicpublished: 20d agoconfidence: 0.95id: f2da3fad-9eae-4370-8978-2ba2278db6fc

Claude Code CLI v2.1.280 ships Claude Opus 5.5 (`claude-opus-5-5`) as the new default Opus model with a 1M-token context and $4/$20 per Mtok pricing ($0.20/Mtok cache reads). Also adds `CLAUDE_CODE_MAX_MCP_DESCRIPTION_LENGTH` to override the 2,048-char cap on MCP tool descriptions/server instructions, richer hook OpenTelemetry events, and dozens of fixes to auto mode, subagents, MCP reconnection, and dialog handling.

capability delta

an agent can now run on Claude Opus 5.5 with 1M-token context via Claude Code, and raise the MCP tool description cap beyond 2,048 chars using CLAUDE_CODE_MAX_MCP_DESCRIPTION_LENGTH.

curator note

Notable: new Opus 5.5 model surfaced via CLI notes; worth cross-checking Anthropic's model API docs for a formal model_release entry.

// install

npm i -g @anthropic-ai/claude-code@2.1.280

npm · @anthropic-ai/claude-code @ 2.1.280

// example

bash

npm i -g @anthropic-ai/claude-code@2.1.280

# Use the new default Opus 5.5 model with 1M context
claude --model claude-opus-5-5

# Raise the MCP tool description cap for a session
export CLAUDE_CODE_MAX_MCP_DESCRIPTION_LENGTH=8192
claude

// links

claude-codeclaude-opus-5-5anthropicclimcpagents1m-context

source: github_release · https://github.com/anthropics/claude-code/releases/tag/v2.1.280