Context and cost

What fills a captain's context window before it reads a line of your code, and what you can cut.

A captain pays for its context on every API call, and most of what it carries is there before it has read a line of your code. These are measured figures from one machine, and the levers are mostly yours.

What you can change#

Measured savings per API call
Change	Saving	How
Trim built-in tools to what a captain uses	11,945	`--tools Bash,Read,Edit,Write,Grep,Glob`
…of which dropping one large tool description alone	8,621	Omit the heaviest tool from --tools
Turn off skills	4,693	`--disable-slash-commands`
…structurally: drop unused plugin bundles	part of the 4,693	Remove them from enabledPlugins. One 36-skill bundle was the largest single block.
Turn off MCP servers	2,603+	`--strict-mcp-config`, or disconnect unused connectors. Measured with 2 of 5 servers connected; the true figure is larger.
Trim the project rulebook	up to 2,628	CLAUDE.md / AGENTS.md. That delta also contains git status, so the editable part is roughly 1,600.
Trim captain role instructions	up to 2,309	The only Captain Barbossa-controlled item on this list.
`--disallowedTools`	0	A measured no-op. It does not remove schemas.

Combined and measured end to end, a captain-equivalent session goes from 34,253 to 15,012 tokens — a 56% cut, and 73% against the real interactive figure of 56,485.

shell

--tools Bash,Read,Edit,Write,Grep,Glob \
  --disable-slash-commands \
  --strict-mcp-config

The irreducible floor#

Measured floors
Floor	Tokens	What it is
Absolute measured floor	5,870	No tools, no skills, no MCP, outside any project. Unusable: the agent cannot read or edit anything.
Usable floor, no captain	12,703	Six file and shell tools, no skills, no MCP, inside a repo.
Usable floor, captain	15,012	The above plus the captain role instructions. A captain cannot go below this and still be a captain.

Of that 15,012, the parts nobody can remove are the 5,870 base prompt and roughly 6,100 of schemas for the six tools a captain needs. The rest is the repo's own rulebook and the captain's role instructions, both of which are editable text.

What only the provider can change#

The base system prompt, the deferred-tool index format (a name plus a description line per tool), the schemas for tools that are not selectable via --tools, and the interactive-only block are all outside your reach. Worth knowing so you stop trying.

Top three, in order#

--tools Bash,Read,Edit,Write,Grep,Glob — 11,945 tokens per call. Most of it is one tool's description at 8,621.
--disable-slash-commands, or uninstall unused plugin bundles — 4,693 tokens.
--strict-mcp-config, or disconnect unused connectors — 2,603 tokens and rising with each server that connects.

Why this matters for a crew#

Every crew pays the same floor. A team of five is five floors, re-sent on every API call each of them makes. That is the arithmetic behind the cheap default in models and the rule in when to recruit — and the dashboard is where you watch it land.