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llmprobe
Synthetic monitoring and CI smoke tests for LLM inference endpoints. Measure TTFT, latency, throughput, and errors. Single binary, zero SDKs.
llmprobe is a CLI tool for LLM serving reliability. It probes hosted APIs or OpenAI-compatible inference servers, then reports the metrics that matter for production user experience: time to first token (TTFT), total latency, generation throughput (tokens/sec), and error rates.
Use it as a one-off health check, a continuous monitor, or a CI gate that blocks deploys when your LLM provider is degraded.

Public benchmark
llm-bench uses llmprobe to run a continuous public benchmark of major LLM APIs. It publishes a live dashboard at bench.jonathanwrede.de and raw JSONL data in Jwrede/llm-bench-data.
This is the intended use case: repeated synthetic probes that make LLM latency, TTFT regressions, throughput drops, and provider degradation visible before users report them.
Install
Download a prebuilt binary from the latest release (Linux, macOS, Windows; amd64 and arm64).
Or install from source:
go install github.com/Jwrede/llmprobe@latest
llmprobe versionClaude Code plugin
Install as a Claude Code plugin for /llmprobe skill and MCP tools:
claude plugin install Jwrede/llmprobeOr register the MCP server directly:
claude mcp add --transport stdio llmprobe -- llmprobe mcpllmprobe runs locally and only contacts LLM endpoints you configure. See PRIVACY.md for details.
Quick start
llmprobe works with OpenAI, Anthropic, Google, Azure OpenAI, AWS Bedrock, and OpenAI-compatible endpoints such as vLLM, Ollama, OpenRouter, Groq, Together AI, Fireworks, DeepSeek, and Mistral.
Create a probes.yml (or copy the included example):
providers:
- name: openai
api_key: ${OPENAI_API_KEY}
models:
- name: gpt-4o
thresholds:
max_ttft: 2s
- name: gpt-4o-mini
thresholds:
max_ttft: 500ms
- name: anthropic
api_key: ${ANTHROPIC_API_KEY}
models:
- name: claude-sonnet-4-20250514
thresholds:
max_ttft: 1sRun a probe:
$ llmprobe probe
Provider Model Status TTFT Latency Tok/s Tokens Error
-------- ----- ------ ---- ------- ----- ------ -----
openai gpt-4o healthy 312ms 2100ms 68.4 42
openai gpt-4o-mini healthy 98ms 814ms 112.3 56
anthropic claude-sonnet-4-20250514 healthy 420ms 2831ms 52.1 38
azure gpt-4o healthy 289ms 1950ms 71.2 44
bedrock anthropic.claude-3-5... degraded 1820ms 4510ms 28.1 38
4 healthy, 1 degraded, 0 errorsWhat it measures
| Metric | What it means |
|---|---|
| TTFT | Time from request send to first content token. This is what users feel as "lag" before the response starts streaming. |
| Latency | Total time from request to stream close. |
| Tok/s | Generation throughput: tokens produced per second after the first token. Calculated as token_count / (latency - ttft). |
| Tokens | Total output tokens. Prefers provider usage metadata when available, falls back to SSE event counting. |
| Status | healthy if all thresholds pass, degraded if any threshold is exceeded, error if the request failed. |
Commands
llmprobe probe
One-off health check. Probes all configured endpoints and prints results.
llmprobe probe # table output
llmprobe probe -f json # JSON output
llmprobe probe --fail-on degraded # exit 1 if any endpoint is degraded
llmprobe probe -c custom-config.yml # custom config pathExit codes for CI:
--fail-on | Exit 0 | Exit 1 |
|---|---|---|
error (default) | healthy or degraded | any error |
degraded | healthy only | degraded or error |
none | always | never |
llmprobe watch
Continuous monitoring. Probes all endpoints on an interval and prints a summary line per iteration.
llmprobe watch # default 60s interval
llmprobe watch --interval 30s # custom interval
llmprobe watch --tui # live terminal dashboard with TTFT chart
llmprobe watch --tui --load data.jsonl # load historical data into the dashboard
llmprobe watch -f json # JSONL output (one line per result)
llmprobe watch --prometheus :9090 # expose Prometheus metrics
llmprobe watch --otel localhost:4317 # export OpenTelemetry metrics via OTLP/gRPCThe --tui flag launches a live terminal dashboard with a TTFT chart,
color legend, and statistics table. Use --load to import historical
JSONL data (from llmprobe watch -f json > data.jsonl).

$ llmprobe watch --interval 30s
Watching 4 endpoints every 30s (Ctrl+C to stop)
[14:01:02] All 4 endpoints healthy.
[14:01:32] All 4 endpoints healthy.
[14:02:02] 3 healthy, 1 degraded, 0 errors. DEGRADED: openai/gpt-4o (TTFT 1820ms)
[14:02:32] All 4 endpoints healthy.llmprobe report
Generate a Markdown summary from JSONL probe data with p50/p95/p99 percentiles for TTFT, latency, and throughput per endpoint.
llmprobe report data.jsonlOutput:
| Provider | Model | Probes | Errors | TTFT p50 | TTFT p95 | ... | Tok/s p50 | ...
|----------|-------|--------|--------|----------|----------|-----|-----------|----
| openai | gpt-4o | 100 | 2 | 115ms | 188ms | ... | 46.9 | ...llmprobe baseline
Create a baseline file from historical JSONL data for regression detection.
llmprobe baseline data.jsonl -o baseline.jsonReference the baseline in your config to use multiplier-based thresholds:
baseline: baseline.json
providers:
- name: openai
api_key: ${OPENAI_API_KEY}
models:
- name: gpt-4o
thresholds:
max_ttft_multiplier: 2.0 # fail if TTFT > 2x baseline p50
max_latency_multiplier: 2.5 # fail if latency > 2.5x baseline p50This lets you detect regressions relative to your own historical data rather than setting absolute thresholds.
llmprobe version
Print the installed binary version.
llmprobe versionCI integration
Use llmprobe probe as a pre-deploy gate:
# .github/workflows/deploy.yml
- name: Check LLM providers
env:
OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}
ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
run: |
go install github.com/Jwrede/llmprobe@latest
llmprobe probe --fail-on degradedThis blocks the deploy if any LLM provider is experiencing degraded performance right now.
When a probe fails, the output shows only the failing endpoints:
Failed endpoints (1/4):
openai/gpt-4o DEGRADED TTFT=280ms Latency=950ms Tok/s=32.1MCP server
llmprobe includes a built-in Model Context Protocol server, allowing Claude Code and other MCP hosts to check LLM API health directly from an agent workflow.
Running the server
llmprobe mcpThis starts the MCP server over stdio.
Registering with Claude Code
claude mcp add --transport stdio llmprobe -- llmprobe mcpOnce registered, Claude Code can call llmprobe tools during any conversation.
Available tools
| Tool | Description |
|---|---|
probe_all | Probe all configured endpoints from probes.yml. Returns TTFT, latency, throughput, and health status for every model. Accepts an optional config parameter for a custom config path. |
probe_model | Probe a single model without a config file. Requires provider, model, and api_key_env. Supports optional base_url for OpenAI-compatible endpoints and optional label for display. |
list_providers | List all providers and models in the config file with their thresholds. Use this to discover available models before probing. |
get_config | Return the full parsed configuration including defaults, providers, models, and thresholds. |
Example use case: An agent calls list_providers to see what models
are configured, then probe_all to verify they are healthy before
deploying changes.
Configuration
defaults:
prompt: "Hello" # probe prompt
max_tokens: 20 # max output tokens
timeout: 30s # per-probe timeout
concurrency: 5 # max parallel probes
providers:
- name: openai # openai, anthropic, google, azure, bedrock
label: openai-prod # optional display name; useful for multiple OpenAI-compatible endpoints
api_key: ${OPENAI_API_KEY} # env var expansion
base_url: https://custom.api # optional, override endpoint
models:
- name: gpt-4o
prompt: "Say hello." # override default prompt
max_tokens: 10 # override default max_tokens
response_format: json # optional; OpenAI-compatible JSON mode
validate_json: true # optional; mark degraded if returned content is not valid JSON
thresholds:
max_ttft: 2s # alert if TTFT exceeds this
max_latency: 10s # alert if total latency exceeds this
min_tokens_per_sec: 20 # alert if throughput drops below this
max_ttft_multiplier: 2.0 # optional; compare against baseline p50
max_latency_multiplier: 2.5
- name: azure
api_key: ${AZURE_OPENAI_API_KEY}
base_url: https://your-resource.openai.azure.com
api_version: "2024-10-21" # optional, defaults to 2024-10-21
models:
- name: gpt-4o # deployment name
- name: bedrock
access_key: ${AWS_ACCESS_KEY_ID}
secret_key: ${AWS_SECRET_ACCESS_KEY}
region: us-east-1
models:
- name: anthropic.claude-3-5-sonnet-20241022-v2:0API keys and AWS credentials support ${ENV_VAR} syntax. Only credential
fields are expanded, so env var references in prompts or model names are
left as-is.
OpenAI-compatible providers
Many providers (Groq, Together AI, Fireworks, DeepSeek, Mistral, OpenRouter,
Ollama, vLLM) expose an OpenAI-compatible API. These work out of the box
by setting base_url. Use the label field to distinguish multiple
OpenAI-compatible blocks:
providers:
# Groq
- name: openai
label: groq
api_key: ${GROQ_API_KEY}
base_url: https://api.groq.com/openai
models:
- name: llama-3.3-70b-versatile
# DeepSeek
- name: openai
label: deepseek
api_key: ${DEEPSEEK_API_KEY}
base_url: https://api.deepseek.com
models:
- name: deepseek-chat
# Together AI
- name: openai
label: together
api_key: ${TOGETHER_API_KEY}
base_url: https://api.together.xyz
models:
- name: meta-llama/Meta-Llama-3.1-70B-Instruct-Turbo
# Local Ollama
- name: openai
label: ollama
api_key: unused
base_url: http://localhost:11434
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