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 agentmods add skills/microsoft/data-formulator/corenpx skills add microsoft/data-formulator --skill coregit clone --depth 1 https://github.com/microsoft/data-formulatorWhat 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 | $0.00026 | $0.05288 |
| Opus 5 | $0.00013 | $0.02644 |
| Sonnet 5 | $0.00005 | $0.01058 |
| Haiku 4.5 | $0.00003 | $0.00529 |
Grade A, and why
core 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 yesterday.
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 — 315 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Core capabilities
This describes the built-in inspection tools you use to gather data and the always-available actions you take on it. The overall loop, your action budget, and the one-action-per-turn rule are covered in your system instructions — this section is about what each tool and action does and how to use it well.
Tools (for data gathering)
- execute_python_script(code) — run a general-purpose Python script to
inspect data, compute stats, transform tables, or verify assumptions. Its
stdout is returned to you (use
print()); the script is for your analysis and its output is never shown to the user. pandas, numpy, duckdb, sklearn, scipy are available. Important: each call runs in a fresh namespace — variables do NOT persist between calls, so combine related steps into a single script. - inspect_source_data(table_names) — get schema, stats, and sample rows for
source tables (cheaper than
execute_python_scriptfor basic inspection). - load_skill(name) — load a skill's instructions into context so you can use the action it unlocks (see the Skills section of your system instructions).
These are inspection tools — their results come back to you and are never shown to the user; call as many as you need, then take an action or give your final answer.
You analyse data that is already in the workspace. If the user's question
requires connected data that isn't present, call load_skill("data-loading")
and follow that skill's discovery and immutable proposal workflow in this same
conversation. Do not hand off to the standalone Data Loading agent.
The initial context already includes sample rows and statistics for each table. If the data is straightforward, go straight to the action without calling tools. Tool results are returned to you before you act.
Actions
Call an action as a tool call when you want to act on the data. Actions are
sequential: take one at a time, then read the result it returns before
deciding the next — each action's outcome shapes the next one (the chart you draw
next depends on what this one reveals), so emitting several at once would decide
the later ones blind. After each result you choose what to do — take another
action, or stop. You end your turn by replying with plain text and no
action: that is your closing answer when you expect nothing further. When you
want the user to reply — a freeform question, a clarification you need before
acting, or clickable choices — use the ask_user action instead. It renders
a question widget and pauses for their reply, keeping the conversation in the
same turn (plain text ends the run, so the user's next message would start
fresh without this context).
What ships with it
3 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.
- yesterday First seen · 315 lines · 26 tokens per session scan A af61f68698da
core is a skill published in the GitHub repository microsoft/data-formulator (17,048 stars, last pushed 3d ago), licensed MIT. It adds 26 tokens to every session and 5,288 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.
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