Clean data skill

Clean Data

Per-row cleanup on a GTM list before any match or enrich call. Profile, standardize, validate. Never destructive: raw input is preserved, invalid rows are tagged with reason codes rather than deleted. Out of scope: deduplication and canonical entity resolution.

Input

$ARGUMENTS is a path to a CSV, Excel, or JSON file. Parse the user message for optional sub-inputs:

• Schema hints if column names are ambiguous: which column is company name, domain, email, phone, country.
• Entity type: companies, contacts, or both. Default: infer from columns.
• Whether to run an MX-record check on email domains (slower, requires DNS). Default: off.
• Whether to produce a match-ready subset for downstream entity resolution. Default: no.

Example phrasings:

• "Clean this leads CSV before I import it to HubSpot."
• "Normalize the company names and domains in /path/accounts.xlsx."
• "Validate the emails in this file and tag the bad rows."
• "Prep this list for prospect matching, only keep contactable corporate rows."
• "Why does my country column have 200 different spellings."

Workflow

1. Copy raw input. Before any transform, copy the input to ./00_raw/<filename> and never write back. All transforms write to numbered phase folders: 01_profiled/, 02_standardized/, 03_validated/. The single most common failure mode in cleanup work is destructive transforms with no path back.

2. Profile the file. Compute fill rate, cardinality, top values, length distribution, and format-pattern frequency for every column. Save the snapshot. Read it before deciding what to clean.

   import pandas as pd
   df = pd.read_csv(input_path)
   profile = pd.DataFrame({
       "fill_rate_pct": (df.notna().mean() * 100).round(1),
       "cardinality": df.nunique(),
       "top_value": df.apply(lambda c: c.dropna().astype(str).mode().iloc[0] if c.dropna().size else None),
       "avg_len": df.apply(lambda c: c.dropna().astype(str).str.len().mean()),
   })
   

   Things to look for: country columns with 200+ distinct values (standardization problem, build ISO Alpha-2 lookup); phone columns where under 50% parse as E.164 (need country hint); company-name 99th-percentile length above 100 chars (pasted addresses, quarantine); free-email providers in the top 5 of email column (decide policy now); fields under 10% fill (probably not worth normalizing); literal strings "NA", "N/A", "None", "null", "-" (collapse to real nulls before validating).

3. Standardize string fields. Run standardization BEFORE validation: a valid email like [email protected] fails naive regex without trim+lowercase first. For every string column do Unicode NFKC, trim, collapse internal whitespace, strip leading and trailing punctuation, collapse null-token strings to real nulls. Then field-specific:

   • Company name. Strip legal suffixes (Inc, LLC, Ltd, GmbH, S.A., 株式会社) at end of string only. Use cleanco if available. Keep BOTH raw and normalized columns.
   • Domain. Strip protocol and www. Fold to the eTLD+1 via tldextract. Flag free-email providers and disposable domains separately.
   • Person name. Parse with nameparser: honorifics, generational suffixes, credentials, particles. If confidence is low, store the raw string with a low-confidence flag.
   • Phone. Format to E.164 with phonenumbers. Hint country from the country column when available.
   • Country. Map free-text to ISO Alpha-2 codes (United States to US, UK to GB, Deutschland to DE). Reusable downstream for country filters.
   • Address. Use libpostal if installed. Country-aware parsing.

   Common mistake: overwriting the display column with the normalized version. Always keep raw alongside normalized.

4. Validate field-by-field. Per field, add a boolean <field>_valid and a <field>_reason text column when invalid. Tag invalid rows; never delete them.

   • Emails: RFC 5322 syntax via email-validator; role-address detection (info@, sales@, noreply@, support@, hello@); disposable-domain check; free-provider flag (gmail, yahoo, qq); optional MX-record check (off by default).
   • Phones: parse + format via phonenumbers. Tag invalid_too_short, invalid_country, invalid_format.
   • Domains: valid eTLD, no IP literals, optional MX check.
   • Country codes: valid ISO Alpha-2 after normalization.

5. Hand off to entity resolution (optional). This skill cleans rows in isolation; it cannot tell you that Starbucks EMEA and Starbucks Corporation point to the same company. If the user wants the handoff, produce a match-ready subset and route rows by available signal:

   • Rows with normalized company name + domain: route to match a business (name + website, falls back to domain-only on mismatch).
   • Rows with a corporate (not role / free-provider / disposable) email: route to match a prospect via email.
   • Rows with parsed person name + company name: route to match a prospect via name + company.
   • Rows with a validated LinkedIn URL: route to match a prospect via LinkedIn.

   Filter out tagged-invalid rows before the handoff so you do not spend credits matching [email protected] or disposable addresses. The returned IDs become the join keys for any later enrich a business or enrich a prospect call.

Output Format

Profile Snapshot

Per column: fill_rate_pct, cardinality, top_value, avg_len. Markdown table. After cleanup, re-run the profile and show before vs after on touched columns.

Standardization Map

Per normalized field: raw column name, normalized column name, 3 to 5 example transformations (" ACME, Inc. " to acme, "WWW.Acme.COM" to acme.com, "+1 (415) 555 1212" to +14155551212).

Validation Verdict

Per validated field: counts of valid, invalid, risky. Frequency table of reason codes (e.g. role_address: 42, disposable_domain: 18, invalid_syntax: 6).

Cleaned File

A single CSV at ./03_validated/<input_name>_clean.csv with all original columns plus <field>_norm, <field>_valid, and <field>_reason columns.

Match-Ready Subset (only if requested)

A second CSV at ./04_match_ready/<input_name>_for_match.csv containing only rows that passed validation, plus a one-line summary of which match path each row subset should route to (count by path).

Limitations

• Does NOT deduplicate or resolve to canonical entities. Two normalized strings can still refer to the same real-world business. Hand off to a match step for that.
• Person-name parsing is best-effort. Non-Western order, hyphenated families, and missing separators are flagged with a low-confidence marker; raw string is always preserved.
• The MX-record check requires DNS and adds 50 to 200ms per unique domain. Off by default.
• Free-email providers (gmail, yahoo) are flagged but cannot be linked to a corporate identity from this skill alone. Pair with a prospect match (email + company) when needed.
• Holding-company and subsidiary pitfalls are out of scope (meta.com vs instagram.com vs whatsapp.com). Resolve via company-hierarchies enrichment after matching.
• If the input lacks a country column entirely, phone normalization defaults to a permissive parser and may mis-format short numbers. Provide a default country in the user message when possible.