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: toolcallexecute(ToolCallExecuteParams::builder()...), llmcallexecute(LlmCallExecuteParams::builder()...) - Python: tools.execute(...), llm.execute(...) - Node.js: toolCallExecute(...), llmCallExecute(...) - Go: tools.Execute(...), llm.Execute(...) or the top-level wrappers

• 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 next pattern 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 LLMRequest made 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(...) and

conditional_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.

Checklist

• Scope boundary chosen before the first tool or LLM call
• Existing tool function wrapped without losing its original arguments/result
• Existing LLM/provider call wrapped at the right abstraction layer
• Optional metadata, attributes, or model name attached where useful
• Context propagation handled if the call hops threads or async tasks

Use Another Skill When

Choose another skill when the task requires a neighboring workflow:

• Use nemo-relay-plugin-observability for traces, ATIF, or export setup.
• Use nemo-relay-debug-runtime-integration to debug missing events or load

failures.

• Use nemo-relay-instrument-context-isolation for per-request isolation or

worker-pool guidance.

• Use nemo-relay-plugin-build for reusable, configuration-activated runtime

behavior.

Related Skills

Use these skills for adjacent workflows:

• Start onboarding with nemo-relay-get-started.
• Add typed wrappers with nemo-relay-instrument-typed-wrappers.
• Configure export with nemo-relay-plugin-observability.
• Package reusable behavior with nemo-relay-plugin-build.