Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/string-os/string/using-stringnpx skills add string-os/string --skill using-stringgit clone --depth 1 https://github.com/string-os/stringWhat 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 | $0.00038 | $0.00350 |
| Opus 5 | $0.00019 | $0.00175 |
| Sonnet 5 | $0.00008 | $0.00070 |
| Haiku 4.5 | $0.00004 | $0.00035 |
Grade A, and why
using-string 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 2d 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
Using String
You have the installed String MCP tool named string; some hosts display it with a server prefix.
Call it with { topic, cmd }, for example { "topic": "main", "cmd": "/info" }.
Use topics like main, app:<name>, app:<name>:<config>, bash:<name>, or hubs app, tool, bash, event, system.
cmd must start with /; use /help, /info, and /act --help to discover what to do.
Use /open to read files, URLs, or apps; installed apps can run /act.<name> directly from app:<name> if you already know the action.
Use /edit to inspect raw files, /write to create or overwrite, /append to add content, and /replace for exact text, block, or line-range edits.
Use /install to add apps; /set $VAR = "..." for app credentials.
Use topic event with /events, /events.read <id>, and /events.ack <id> to handle local webhook messages.
Claude Code may also receive those webhook messages through the String channel, but ack still happens with /events.ack <id>.
Read the payload inside <𝒞=string:TOPIC>...</𝒞> and follow Recovery: or next: hints.
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.
- 2d ago First seen · 29 lines · 38 tokens per session scan A 4353f6cf49a6
using-string is a skill published in the GitHub repository string-os/string (65 stars, last pushed 13d ago), licensed MIT. It adds 38 tokens to every session and 350 once invoked, about $0.0002 per session on Opus 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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