instrument

instrument is a command for coding agents from pydantic/skills. It costs 15 tokens per session (696 once invoked), scanned A, original, MIT.

A project command that detects supported programming languages and frameworks, then adds Logfire monitoring. It supports Python, JavaScript or TypeScript, and Rust, including projects that use more than one language.

In plain words
What is it for?
Use it to instrument detected web frameworks, databases, HTTP clients, AI libraries, and other supported libraries by scanning the project's dependency files and adding the required configuration.
Why use it?
It removes the manual work of finding the application entry point, selecting Logfire packages, and placing setup calls in the correct order.

Command

Part of the logfire plugin — 3 skills, 4 commands, 1 MCP server shipped together

Install

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.

agentmods
npx agentmods add commands/pydantic/skills/instrument
Clone the repo
git clone --depth 1 https://github.com/pydantic/skills

Or install logfire, the plugin that ships this one along with the rest of its 3 skills, 4 commands, 1 MCP server.

Wrote 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.

agentmods badge for instrument

README.md
[![agentmods](https://agentmods.dev/badge/commands/pydantic/skills/instrument.svg)](https://agentmods.dev/commands/pydantic/skills/instrument)
Your own site
<a href="https://agentmods.dev/commands/pydantic/skills/instrument"><img src="https://agentmods.dev/badge/commands/pydantic/skills/instrument.svg" alt="Measured on agentmods" height="20"></a>
Per session 15 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 696 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00015 $0.00696
Opus 5 $0.00008 $0.00348
Sonnet 5 $0.00003 $0.00139
Haiku 4.5 $0.00002 $0.00070

Measured 4d ago against content hash f41cd594def7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

instrument 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 4d 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.

plugins/logfire/commands/instrument.md · 56 lines

How it starts

The opening of the file, as written. The whole thing — 56 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/instrument

Add Logfire observability to the current project. Supports Python, JavaScript/TypeScript, and Rust - including polyglot projects.

Workflow

  1. Detect languages and frameworks: Scan the project root for language indicators and dependency files:

    • pyproject.toml, requirements.txt - Python
    • package.json - JavaScript/TypeScript
    • Cargo.toml - Rust
    • A project may use multiple languages (e.g., Python backend + JS frontend). Instrument each.
  2. For each detected language, follow the appropriate setup:

Python

  • Identify instrumentable libraries from dependencies (FastAPI, httpx, asyncpg, SQLAlchemy, PydanticAI, OpenAI, Django, Flask, etc.)
  • Install logfire with matching extras: uv add 'logfire[<detected-extras>]'. Check for uv.lock (uv), poetry.lock (poetry), or Pipfile.lock (pipenv) to pick the right package manager.
  • Find the application entry point and add:
    • import logfire at the top
    • logfire.configure() - must come before any instrument_*() calls
    • logfire.instrument_<library>() calls for each detected framework
    • Web framework instrumentors (instrument_fastapi, instrument_django, instrument_flask) need the app instance. HTTP client and database instrumentors are global.

JavaScript / TypeScript

  • Check package.json for framework (Express, Next.js, Fastify, etc.) and runtime (Node.js, Cloudflare Workers, Deno).
  • Install the appropriate package:
    • Node.js: npm install @pydantic/logfire-node
    • Cloudflare Workers: npm install @pydantic/logfire-cf-workers logfire
    • Next.js / generic: npm install logfire
  • Add instrumentation based on runtime:
    • Node.js: Create instrumentation.ts with import * as logfire from '@pydantic/logfire-node' and logfire.configure(). Add --require ./instrumentation.js to the start script.
    • Cloudflare Workers: Wrap the handler with instrument() from @pydantic/logfire-cf-workers.
    • Next.js: Set OTEL_EXPORTER_OTLP_TRACES_ENDPOINT and OTEL_EXPORTER_OTLP_HEADERS in .env.local.

Read the full file on GitHub · 56 lines

Changes

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.

  1. 4d ago First seen · 56 lines · 15 tokens per session scan A f41cd594def7

Subscribe to this mod's changes

instrument is a command published in the GitHub repository pydantic/skills (127 stars, last pushed 5d ago), licensed MIT. It adds 15 tokens to every session and 696 once invoked, about $0.0001 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.