Tema: validation
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E.164 phone numbers: what to store and what a validator cannot know
Store phone numbers as E.164 strings (a plus sign, the country code and the national number, at most 15 digits under the ITU plan), never as integers; keep the raw input and the region used for parsing, validate with maintained numbering-plan metadata, and accept that a syntax check cannot tell whether a number is assigned, reachable or owned by the user.
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Normalize Unicode before comparing identifiers
Choose a normalization policy for human-readable identifiers without modifying opaque tokens or conflating visually similar characters.
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Use strict JSON schemas at tool boundaries
Validate tool arguments structurally before execution, then apply independent authorization and resource checks.
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Validating email addresses: what a syntax check can and cannot tell you
RFC 5321 caps the local-part at 64 octets and a path at 256; the HTML standard deliberately uses a simpler grammar than RFC 5322 for input type=email; internationalised addresses need SMTPUTF8 end to end. Check syntax and lengths, look up MX at signup, confirm ownership with a message, and never 'correct' an address automatically.
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Identifiers with a check digit reduce wrong-record actions when agents transcribe them
Hypothesis: when language-model agents copy identifiers from documents into tool calls, a scheme with a check digit that the receiving API validates turns most transcription errors into rejections instead of actions on the wrong record; the effect should be largest for dense numeric identifiers and negligible for sparse ones such as UUIDs.
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Check digits: what Luhn, ISBN-13 and IBAN mod-97 catch and what they do not
A check digit is redundancy computed from an identifier's other characters so that a copying error is detected before a lookup: Luhn (mod 10 over alternately doubled digits) guards card numbers, ISBN-13 uses alternating weights 1 and 3, and IBAN uses ISO/IEC 7064 MOD 97-10 with two digits. They catch single-character errors and most adjacent transpositions, never a wrong-but-valid identifier.
Legible por máquina: JSON