From c4766ac1a57a69c745803eab36228c7ccce37ac5 Mon Sep 17 00:00:00 2001
From: jared <jaredmswanson@gmail.com>
Date: Wed, 8 Jul 2026 14:35:04 -0400
Subject: [PATCH] vault: session notes 2026-07-08

---
 journal/2026-07-08.md                         |  7 +++++
 ...e-code-tool-schema-costs-and-yagni-deny.md | 31 +++++++++++++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 reference/claude-code-tool-schema-costs-and-yagni-deny.md

diff --git a/journal/2026-07-08.md b/journal/2026-07-08.md
index e24c0b7..c632901 100644
--- a/journal/2026-07-08.md
+++ b/journal/2026-07-08.md
@@ -387,3 +387,10 @@ tags: [scope/global, type/log]
 **Reason:** other
 **Vault notes touched:**
 (none)
+
+## Session — 2026-07-08T18:25:07Z
+
+**Project:** /tmp/claude-1000/-home-jared-dev-cc-os/4db8af72-9bf6-4587-9249-17d5361849ec/scratchpad/b2measure
+**Reason:** other
+**Vault notes touched:**
+(none)
diff --git a/reference/claude-code-tool-schema-costs-and-yagni-deny.md b/reference/claude-code-tool-schema-costs-and-yagni-deny.md
new file mode 100644
index 0000000..a3ba1af
--- /dev/null
+++ b/reference/claude-code-tool-schema-costs-and-yagni-deny.md
@@ -0,0 +1,31 @@
+---
+summary: Claude Code's non-deferred built-in tool schemas cost ~18k tokens/session; the Workflow schema alone is ~6k, and a permissions.deny block in settings.json removes unused tools' schemas entirely (measured −6.5k for four never-used tools).
+tags:
+  - type/reference
+  - tool/claude-code
+scope: global
+type: reference
+source: cc-os docs/plans/b2-profile-overlays.md (follow-on section, 2026-07-08)
+date: 2026-07-08
+last_updated: 2026-07-08
+---
+
+# Claude Code tool schemas: where the ~18k goes, and the YAGNI deny lever
+
+Measured 2026-07-08 (headless haiku, `--output-format json` usage totals).
+
+- The ~29k empty-dir context floor = ~6.3k system-prompt text + **~18k built-in tool
+  schemas** + ~4.8k user stack. ToolSearch deferral only covers the optional tier
+  (Cron, LSP, NotebookEdit, Monitor, web tools…) — core schemas ship every request.
+- **Workflow's schema alone is ~6k tokens** (−5,982 when disallowed) — about the size
+  of the entire system-prompt text.
+- `"permissions": {"deny": ["Workflow", ...]}` in `~/.claude/settings.json` removes the
+  denied tools' schemas from context, identical to `--disallowedTools` (22,532 vs
+  22,536 measured) — so a global deny needs no wrapper or flags.
+- Ground truth for "which tools do I actually use": count `tool_use` names across
+  `~/.claude/projects/**/*.jsonl` transcripts. Five weeks of data (2026-06→07) showed
+  zero-or-one lifetime calls to Workflow, Artifact, SendUserFile, ReportFindings →
+  denied globally (−6.5k/session). Revert by removing the deny entry if Workflow
+  ("ultracode" multi-agent orchestration) is ever wanted.
+
+Related: [[claude-code-setting-sources-silent-plugin-drop]], [[cc-os-hub]]