vLLM Semantic Router is a programmable routing layer that chooses or combines language models for each request in a system using multiple models and types of computing infrastructure. It helps teams route inference by signals such as user preferences, application policies, quality, cost, latency, privacy, and safety requirements. The catalogue skills and instructions support configuring and operating this model-routing system.
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 vllm-project/semantic-router --skill vllm-sr-agent-operationsgit clone --depth 1 https://github.com/vllm-project/semantic-routerWrote 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/vllm-project/semantic-router/vllm-sr-agent-operations)<a href="https://agentmods.dev/skills/vllm-project/semantic-router/vllm-sr-agent-operations"><img src="https://agentmods.dev/badge/skills/vllm-project/semantic-router/vllm-sr-agent-operations/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/vllm-project/semantic-router/vllm-sr-agent-operations"><img src="https://agentmods.dev/badge/skills/vllm-project/semantic-router/vllm-sr-agent-operations.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 | $0.00074 | $0.04476 |
| Opus 5.5 | $0.00030 | $0.01790 |
| Sonnet 5.5 | $0.00015 | $0.00895 |
| Haiku 4.5 | $0.00007 | $0.00448 |
Grade C, and why
vllm-sr-agent-operations scanned grade C with 3 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 6d 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.
Sends data to an external URLmediumData exfiltration
A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.
curl -fsS http://127.0.0.1:9099/v1/systemone -H 'content-type: application/json' -d '{ Asks for rootmediumPrivilege escalation
A mod that escalates privileges can change anything on the machine, not only the project.
| Python | 3.10 or newer, and `ensurepip` prints `pip …` | Ubuntu and Debian: with the user's OK, `sudo apt-get install -y python3-venv`. Without it the installer stops at "ensurepip is not available". | Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl -s -m 3 http://127.0.0.1:11434/api/tags # Ollama: its model names How it starts
The opening of the file, as written. The whole thing — 343 lines — stays where its author put it; the contents beside it link to each section on GitHub.
vLLM Semantic Router: install, configure, verify
Run the steps in order. Each one says what to run, what success looks like and what to do otherwise, and each is safe to run again.
The Router serves an OpenAI-compatible API and picks a model for each request.
It does not run the models that answer users; those are the user's endpoints,
such as vLLM, Ollama or a hosted API. vllm-sr serve runs a stack in Docker:
the Router (inference on port 8899, management API on 8080), the Dashboard
(8700), the model runtime for the Router's own classifiers, and supporting
services.
Ground rules
- Keep secrets in environment variables, never in YAML, command arguments, logs or your report.
- Don't stop, restart or replace what you didn't start (containers, a running
vllm-srstack, services on its ports) without asking. - Ask before system-wide changes: installing packages, adding the user to a group, publishing a port beyond loopback.
- Never run
vllm-sr servewithout a complete--config. Without one it starts the Dashboard's setup mode and waits for a person indefinitely. - An HTTP 200 alone is not success. Each check below names what the output must contain.
1. Preflight
These commands change nothing. Run them and keep the results.
uname -sm
docker info --format '{{.ServerVersion}}'
python3 -c 'import sys; print(sys.version.split()[0])'
python3 -m ensurepip --version
df -h "$HOME" | tail -1
ls /dev/kfd /dev/dri/render* 2>/dev/null
nvidia-smi -L 2>/dev/null
vllm-sr --version 2>/dev/null && vllm-sr status
| Check | Pass | Otherwise |
|---|---|---|
| Docker | prints a version | "permission denied": ask the user to add their account to the docker group. Not installed: ask before installing it. Podman works too: add --container-runtime podman to vllm-sr commands. |
| Python | 3.10 or newer, and ensurepip prints pip … |
Ubuntu and Debian: with the user's OK, sudo apt-get install -y python3-venv. Without it the installer stops at "ensurepip is not available". |
| Disk | 10 GB free; 30 GB for a GPU platform | Ask the user. |
vllm-sr |
not installed, or status says Not running |
A stack is already running. It is the user's: find its directory (below), verify it with step 6 using its own decision and model names, and ask before changing it. |
What ships with it
7 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.
- 6d ago Changed 86403332c36c
- 20d ago Changed · +9 lines f6b1e98f5afa
- 22d ago Changed · +278 lines · +24 tokens per session scan A → C 25d7c3d9c341
- 1mo ago Changed 4c3c7f2d77c3
- 1mo ago Changed · -76 lines · +8 tokens per session 64b536d37db2
- 1mo ago Changed · -119 lines · -7 tokens per session 9a08faea605e
- 1mo ago Changed · +8 lines b20c21bdde39
- 1mo ago Changed · +157 lines · -44 tokens per session 5e6522363803
- 1mo ago Changed · +7 lines 14c244c6d003
- 1mo ago First seen · 79 lines · 93 tokens per session scan A e3dce6c5deea
vllm-sr-agent-operations is a skill published in the GitHub repository vllm-project/semantic-router (6,328 stars, last pushed today), licensed Apache-2.0. It adds 74 tokens to every session and 4,476 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it C with 3 findings (sends data to an external url, asks for root, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-12.
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