NVIDIA/NeMo-Relay is a runtime and library that gives coding agents and applications shared control over agent execution scopes, policies, plugins, lifecycle events, and observability data. It is for developers who need to inspect or instrument runs from agents such as Codex or Claude Code, or integrate frameworks and export traces and trajectories. The catalogue entries provide Relay plugins, hooks, instructions, skills, and an MCP server for those workflows.
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 NVIDIA/NeMo-Relay --skill nemo-relay-instrument-callsgit clone --depth 1 https://github.com/NVIDIA/NeMo-RelayWrote 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/nvidia/nemo-relay/nemo-relay-instrument-calls)<a href="https://agentmods.dev/skills/nvidia/nemo-relay/nemo-relay-instrument-calls"><img src="https://agentmods.dev/badge/skills/nvidia/nemo-relay/nemo-relay-instrument-calls/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/nvidia/nemo-relay/nemo-relay-instrument-calls"><img src="https://agentmods.dev/badge/skills/nvidia/nemo-relay/nemo-relay-instrument-calls.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00047 | $0.00882 |
| Opus 5 | $0.00023 | $0.00441 |
| Sonnet 5 | $0.00009 | $0.00176 |
| Haiku 4.5 | $0.00005 | $0.00088 |
Grade A, and why
nemo-relay-instrument-calls 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 10d 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.
How it starts
The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Instrument Tool And LLM Calls
Use this skill when an app already has tool functions or model/provider calls and needs to run them through NeMo Relay correctly. Keep the original callable behavior stable while adding Relay lifecycle capture.
Default Guidance
- Put a scope around the natural agent, request, workflow, or graph boundary.
- Use managed execution APIs first:
- Rust:
tool_call_execute(ToolCallExecuteParams::builder()...),llm_call_execute(LlmCallExecuteParams::builder()...) - Python:
tools.execute(...),llm.execute(...) - Node.js:
toolCallExecute(...),llmCallExecute(...) - Go:
tools.Execute(...),llm.Execute(...)or the top-level wrappers
- Rust:
- Use manual lifecycle APIs only when the host framework cannot be wrapped by the managed execute helpers.
Embedded Runtime Semantics
- Managed tool and LLM execution runs conditional-execution guardrails first on the raw input. If rejected, the runtime emits a standalone mark event and does not run request intercepts or the callable.
- Request intercepts run after conditional guardrails and rewrite the real input that reaches execution intercepts and the callback.
- Sanitize-request guardrails affect emitted start-event payloads only. They do not rewrite the caller-visible request or arguments.
- Execution intercepts wrap the callback with the middleware
nextpattern and may short-circuit by returning their own result. - Sanitize-response guardrails affect emitted end-event payloads only. The value returned to application code remains the raw callback or execution-intercept result.
- If execution fails after the start event has been emitted, the runtime still emits an end event without a semantic output payload.
- Tool calls are named operations with JSON-compatible arguments and results. Keep the original tool callable responsible for business logic; let NeMo Relay own lifecycle events, middleware, and metadata.
- LLM calls use an
LLMRequestmade of metadata plus content. Pass model names and stable call identifiers when they matter for trace export or diagnostics. - Manual lifecycle APIs are for framework adapters that already own execution. If you use them, every start call needs a matching end or error path with the relevant semantic payloads supplied explicitly.
- Partial middleware APIs such as
request_intercepts(...)andconditional_execution(...)are for advanced adapters that need one middleware family before calling a provider manually. - Streaming LLM wrappers collect chunks and finalize a response at stream end; dropping the stream early can prevent finalizers and subscribers from seeing a complete output.
What ships with it
4 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.
- 10d ago First seen · 86 lines · 47 tokens per session scan A ccb99a894d33
nemo-relay-instrument-calls is a skill published in the GitHub repository NVIDIA/NeMo-Relay (168 stars, last pushed today), licensed Apache-2.0. It adds 47 tokens to every session and 882 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.
Other skills, from other repositories
event-store-design
Design and implement event stores for event-sourced systems. Use when building event sourcing infrastructure, choosing event store technologies, or implementing event persistence patterns.
cqrs-implementation
Implement Command Query Responsibility Segregation for scalable architectures. Use when separating read and write models, optimizing query performance, or building event-sourced systems.
workflow-orchestration-patterns
Design durable workflows with Temporal for distributed systems. Covers workflow vs activity separation, saga patterns, state management, and determinism constraints. Use when building long-running processes, distributed transactions, or microservice orchestration.
microservices-patterns
Design microservices architectures with service boundaries, event-driven communication, and resilience patterns. Use when building distributed systems, decomposing monoliths, or implementing microservices.
python-sdk
Implement or modify Python SDK behavior under python/composio, including tools, toolkits, sessions, auth configs, connected accounts, client integration, and shared Python models. Use for Python core runtime/API work; pair with python-testing and cross-sdk-parity when TypeScript must match.
azure-eventhub-dotnet
Azure Event Hubs SDK for .NET. Use for high-throughput event streaming: sending events (EventHubProducerClient, EventHubBufferedProducerClient), receiving events (EventProcessorClient with checkpointing), partition management, and real-time data ingestion. Triggers: "Event Hubs", "event streaming"…