telemetrylisted

# Telemetry A PostToolUse hook writes one line per tool call to `.claude/reports/telemetry-YYYY-MM-DD.jsonl`. **Metadata only** — timestamp, session, cwd, tool name, input and output *sizes*, and whether the call succeeded. No tool input or output content is ever written, which is what makes it safe to leave on in a repo that handles credentials; the hook's suite asserts that by feeding a canary secret through and grepping the log for it. ## Reading it ```bash node "${CLAUDE_PLUGIN_ROOT}/scripts/telemetry-report.js" # today node "${CLAUDE_PLUGIN_ROOT}/scripts/telemetry-report.js" --days=7 # the week node "${CLAUDE_PLUGIN_ROOT}/scripts/telemetry-report.js" --days=0 # everything ``` It prints the event count, distinct tools, per-day totals, and a per-tool table of calls and kilobytes, biggest first. ## Interpreting it The number that usually matters is **KB per tool**, not calls. Fifty `Bash` calls returning a line each are cheap; three `Read`s of a lockfile are not. A session that feels slow and shows most of its bytes in `Read` is usually one where a targeted `Grep` would have done. `failed` counts in the last column are a rough signal — the hook infers success from the absence of an error marker, so treat a nonzero count as "look at what happened", not as an exact figure. A day missing from the table means no tool calls were recorded, which is not the same as no work: if the hook is disabled or not installed, every day is missing. Check that the current d