claude-code

Anthropic's agent, and the default runtime. Runs claude -p with a fixed tool allowlist (Bash, Edit, Write, Read, Glob, Grep, WebFetch, notebooks, todos, sub-agents) plus mcp__<server>__* for each MCP server you declare. Versions are pinned and bumped deliberately.

Providers	`anthropic`, `bedrock`, `openrouter`, `vllm`
Model ids	Bare on Anthropic and Bedrock (`claude-sonnet-5`, `anthropic.claude-sonnet-5`); vendor-namespaced on OpenRouter (`anthropic/claude-sonnet-5`); verbatim on a custom endpoint.
MCP	Yes. Written to `/app/.mcp.json`; URL servers get a bearer header from `mcp_auth_tokens`.
Usage	Yes, including cache read and cache creation tokens.
agent_env	`ANTHROPIC_AUTH_TOKEN` for custom endpoints that only accept a bearer token; `ANTHROPIC_CUSTOM_HEADERS` to add request headers.

vllm here means any endpoint that speaks the Anthropic Messages API (a LiteLLM proxy, Bedrock Mantle's /anthropic path). The SDK appends /v1/messages itself, so VLLM_BASE_URL is the segment before that. On OpenRouter every request carries the run id as x-session-id, so traces group per run in OpenRouter's dashboard.

agent: claude-code
model: anthropic/claude-sonnet-5
model_provider: openrouter

Back: Runtime Configuration — the full comparison table, frontmatter defaults, and per-run overrides.