Hermes Agent is an AI assistant that learns from its use by creating and improving skills, retaining knowledge, searching past conversations, and adapting to its users. It is for people who want to run an agent through a terminal or messaging platforms while connecting it to different AI models and scheduled tasks.
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 skills add NousResearch/hermes-agent --skill har-derived-api-clientgit clone --depth 1 https://github.com/NousResearch/hermes-agentWrote 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/nousresearch/hermes-agent/har-derived-api-client)<a href="https://agentmods.dev/skills/nousresearch/hermes-agent/har-derived-api-client"><img src="https://agentmods.dev/badge/skills/nousresearch/hermes-agent/har-derived-api-client.svg" alt="Measured on agentmods" 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 | $0.00019 | $0.02640 |
| Opus 5 | $0.00010 | $0.01320 |
| Sonnet 5 | $0.00004 | $0.00528 |
| Haiku 4.5 | $0.00002 | $0.00264 |
Grade A, and why
har-derived-api-client scanned grade A with 1 finding 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 3d 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
is pure stdlib, replay needs only `requests`/`httpx` (or `curl`). Copies of this mod
2 near-identical copies found in the catalogue:
- har-derived-api-client — 100% identical, 0 lines differ
- har-derived-api-client — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.
HAR-Derived API Client
Drive a website once with a real browser while recording its network traffic to a HAR file, then distill that HAR into the site's private JSON API so you can call it directly with plain HTTP — far cheaper and faster than browser-controlling the page on every request. Credit: trick by Jared Longster, popularized by Dax (thdxr). This captures and replays; it does NOT bypass auth, solve CAPTCHAs, or defeat bot-detection — if the site needs a logged-in session, you carry its headers/cookies forward, you don't forge them.
The scripts are stdlib-plus-Playwright: capture needs Playwright, derivation
is pure stdlib, replay needs only requests/httpx (or curl).
Covers every Hermes browser pathway: the default local browser_navigate
backend, plus the cloud/remote backends (Browserbase, Browser-Use, Firecrawl)
and any /browser connect CDP endpoint. There are two capture scripts — one
for a browser you launch, one for a browser you attach to over CDP — because
HAR recording works differently in each case (see How to Run).
When to Use
- "Build a CLI/client for " — derive its API instead of scripting clicks.
- "This site has no public API but the page clearly fetches JSON."
- You're about to loop
browser_navigatefor the same query repeatedly — stop and derive the endpoint once. - Reverse-engineering an autocomplete, search, feed, or checkout XHR.
- You captured a session on a cloud backend (Browserbase / Browser-Use / Firecrawl) or via
/browser connectand want the API without re-renting the browser.
Prerequisites
- Playwright + a browser binary (capture step only):
pip install playwrightthenplaywright install chromium- (If a system Playwright already has browsers under
~/.cache/ms-playwright, reuse it.)
requestsorhttpxfor the replay step (stdliburllibalso works).- No API keys. Any keys/tokens the client needs are the ones the HAR captured.
- For the CDP path (
har_capture_cdp.py): a reachable CDP endpoint. On Hermes, run/browser connectto print the active endpoint, or readBROWSER_CDP_URL/browser.cdp_urlin config. Cloud backends expose it ascdpUrl/connectUrl.
What ships with it
3 files 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.
- 3d ago First seen · 164 lines · 19 tokens per session scan A 62b411a3c5ba
har-derived-api-client is a skill published in the GitHub repository NousResearch/hermes-agent (242,093 stars, last pushed today), licensed MIT. It adds 19 tokens to every session and 2,640 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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