Tools

Me Write Code ships seven built-in tools, plus dynamic tools loaded from MCP servers and skills. All tool output is run through Caveman Mode compression before re-entering the model's context.

Built-in tools

Tool	Purpose	Default mode access
Read	Read a file or range of lines	always
Find / Ls	Locate files and list directories	always
Grep	Search file contents (ripgrep-backed)	always
Bash	Run shell commands	gated by sandbox/approval settings
Edit	Find/replace edit on a file	gated by approval settings
Write	Write a file	gated by approval settings
Task / Agent	Dispatch a subagent	always

Plan mode restricts to read-only tools (Read, Find, Ls, Grep, and safe Bash). Enable with /plan in the TUI. See Plan Mode.

Caveman Mode compression

Four compression layers reduce repeated and verbose context. Exact savings depend on provider, model, and task; the public benchmark is under revalidation.

Layer	What happens	Impact
Caveman Mode	Model responds in terse technical fragments. Levels: lite, full, ultra.	Prompt + response compression
Tool Budgets	Per-tool line limits (bash: 80, read: 300, grep: 120) + ANSI strip + blank collapse + semantic JSON/XML extraction	-67% to -94% on tool output
Read Dedup	Files fingerprinted per session — re-reads return a stub, not the content	-99% on repeated reads
RTK	Optional Rust binary rewrites bash output before it enters context	~60% additional reduction

Per-tool budgets

{
    "tools": {
        "budgets": {
            "bash": { "maxLines": 80, "stripAnsi": true },
            "read": { "maxLines": 300, "dedupeAcrossSession": true },
            "grep": { "maxLines": 120 }
        }
    }
}

Override per session with --max-tool-lines 200. Override globally in ~/.mewrite/agent/settings.json.

Cost transparency

Per-message inline:

[$0.0042 (cached: $0.0001)] Sonnet 4 · 12,431 in / 412 out

Session summary on /exit:

session: 32 turns · 2h 14m
total: $1.84 — cache + compression savings reported separately
breakdown:
  system    +1,200 tokens
  repomap     +840
  history  +12,150
  files     +8,421
  tools    +18,902 (compressed)

/tokens opens a live breakdown panel.

Daily/weekly totals persist locally and include completed assistant messages from active, unclosed sessions. Legacy closed-session totals live in ~/.cave/cost-totals.json; new per-message records live in ~/.cave/cost-ledger.jsonl. After upgrade, pre-upgrade turns in still-open sessions are not backfilled and may remain missing from /cost; new completed assistant messages are counted going forward.

ToolSearch (deferred MCP schemas)

By default, MCP tools are listed by name only. The model fetches the schema via ToolSearch only when needed. This is the same trick Anthropic uses to cut 85% of context bloat.

Registry

Provider, model, and tool defaults ship with Me Write Code and can be refreshed without upgrading the CLI:

mewrite models update

Override locally in ~/.mewrite/agent/registry.json.