Data Formulator is an interactive workspace where AI agents connect to data sources, answer questions, and create visualizations. It is used to explore and analyze data while branching into related questions without losing the context of each investigative path.
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.
git clone --depth 1 https://github.com/microsoft/data-formulatorWrote 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/rules/microsoft/data-formulator/dev-guides-first)<a href="https://agentmods.dev/rules/microsoft/data-formulator/dev-guides-first"><img src="https://agentmods.dev/badge/rules/microsoft/data-formulator/dev-guides-first/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/rules/microsoft/data-formulator/dev-guides-first"><img src="https://agentmods.dev/badge/rules/microsoft/data-formulator/dev-guides-first.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.01028 | $0.01028 |
| Opus 5.5 | $0.00411 | $0.00411 |
| Sonnet 5.5 | $0.00206 | $0.00206 |
| Haiku 4.5 | $0.00103 | $0.00103 |
Grade A, and why
dev-guides-first 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 1mo 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 — 71 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Dev Guides First
Before Starting Any Development
Before implementing or designing a new feature, module, or significant change, always
read the relevant documents in docs/dev-guides/ to understand existing conventions:
| Guide | When to Read |
|---|---|
docs/dev-guides/1-streaming-protocol.md |
Any work on streaming endpoints or NDJSON protocol |
docs/dev-guides/2-log-sanitization.md |
Any work involving logging, credentials, external services, or DataLoaders |
docs/dev-guides/3-data-loader-development.md |
Any work on ExternalDataLoader, DataConnector, or connector routes |
docs/dev-guides/4-authentication-oidc-tokenstore.md |
Any work on OIDC, TokenStore, AUTH_MODE, or SSO flows |
docs/dev-guides/6-i18n-language-injection.md |
Any work on Agent prompts, Agent routes, backend user-visible messages, or frontend i18n |
docs/dev-guides/7-unified-error-handling.md |
Any work on API errors, frontend API calls, streaming error events, or error tests |
docs/dev-guides/8-path-safety.md |
Any work on backend file access, downloads, Workspace paths, Agent tools, DataLoaders, or sandbox config |
docs/dev-guides/10-agent-knowledge-reasoning-log.md |
Any work on Agent knowledge injection, KnowledgeStore, reasoning logs, or experience distillation |
docs/dev-guides/11-catalog-metadata-sync.md |
Any work on catalog sync, catalog_cache, catalog_annotations, metadata merge, Agent catalog tools, or frontend catalog browsing |
docs/dev-guides/12-sandbox-session.md |
Any work on sandbox execution, Agent tool-calling loops, explore/execute_python code execution, or namespace management |
docs/dev-guides/13-unified-row-limits.md |
Any work on row limits, data loading size caps, frontendRowLimit, MAX_IMPORT_ROWS, or DataLoader size parameter |
docs/dev-guides/14-model-capability-runtime-degradation.md |
Any work on LLM Client calls, Agent LLM invocations, model capability checks, reasoning_effort, or image/vision degradation |
docs/dev-guides/15-dataframe-serialization.md |
Any work on DataFrame→JSON serialization, Agent result rows, DataLoader sample_rows, or table API responses |
.cursor/rules/i18n-no-hardcoded-strings.mdc |
Any work adding or changing user-visible strings in src/ |
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.
- 1mo ago First seen · 71 lines · 1,028 tokens per session scan A fb84b0b53e2c
dev-guides-first is a cursor rule published in the GitHub repository microsoft/data-formulator (17,610 stars, last pushed today), licensed MIT. It adds 1,028 tokens to every session, about $0.0041 per session on Opus 5.5. 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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