Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add leandroz/claude-plugins/plugin install session-statsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/leandroz/claude-plugins/session-stats)<a href="https://agentmods.dev/skills/leandroz/claude-plugins/session-stats"><img src="https://agentmods.dev/badge/skills/leandroz/claude-plugins/session-stats/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/leandroz/claude-plugins/session-stats"><img src="https://agentmods.dev/badge/skills/leandroz/claude-plugins/session-stats.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00053 | $0.00465 |
| Opus 5.5 | $0.00021 | $0.00186 |
| Sonnet 5.5 | $0.00011 | $0.00093 |
| Haiku 4.5 | $0.00005 | $0.00047 |
Grade A, and why
session-stats scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
Session stats
Run the script next to this file and interpret what comes back:
python3 scripts/session_stats.py
When installed as a plugin the path is ${CLAUDE_PLUGIN_ROOT}/skills/session-stats/scripts/session_stats.py. It reads every .jsonl under ~/.claude/projects/ and takes no arguments.
Reading the output
The one thing that trips people up: total tokens is dominated by cache reads, which are re-counted on every assistant turn. A session showing hundreds of millions of "tokens" was not billed at that scale and did not process that much unique text — it means a large context was re-read many times. Output tokens and message count are the honest measures of how much work a session actually did; the total is best used as a relative signal of context weight, comparing sessions against each other rather than against an absolute number.
With that in mind, give the user a real read of their data rather than a restatement of the table:
- Which sessions look like they ran into context trouble — outlier context weight, or long duration paired with a high message count. Compare against the rest of their distribution, since what counts as heavy varies a lot between users.
- Which projects consume disproportionate context relative to how much they're used. Those are the candidates for a leaner CLAUDE.md or for pulling detail into skills that load on demand.
- Whether sessions are trending heavier over time, and whether one project drives the trend.
Then suggest fixes that follow from what you actually saw. Sessions that balloon in context usually want /clear at natural task boundaries or /compact before auto-compaction fires. Heavy cache-creation relative to peers points at a large always-loaded CLAUDE.md. Many tool calls per session points at verbose operations worth delegating to subagents. Very long single sessions are usually less effective than several focused ones — say so when the data shows it, and skip it when it doesn't.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago Changed · +25 tokens per session 0e3818f785a5
- 2mo ago First seen · 27 lines · 28 tokens per session scan A 2a1fb9061e89
session-stats is a skill published in the GitHub repository leandroz/claude-plugins (15 stars, last pushed 1mo ago), licensed MIT. It adds 53 tokens to every session and 465 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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