CSV schema check

csv-schema-check · version 1.0.0 · CSV & tables · free, no key needed

Validate a CSV document against an ordered column list and per-column string constraints.

Use when you need to: csv schema check · validate csv columns · check csv column constraints.

Supported

• csv schema check
• validate csv columns
• check csv column constraints

Not supported

• infer types
• coerce values
• locale number formats
• regex cell patterns
• json schema
• read files
• fetch urls

Behavior

• The first CSV record is the header row; parse failures throw.
• columns.name list must equal the CSV headers in order; a mismatch reports one header_mismatch at row 0 and does not check data rows.
• any accepts every cell including empty; nonempty requires cell length greater than 0.
• integer accepts canonical integer strings including -0, with at most 1000 digits excluding sign; empty fails.
• decimal is a string grammar check: optional ASCII minus, digits, optional single dot with a digit on at least one side, no exponent, at most 1000 characters; empty fails.
• No trimming, case folding, type coercion, or locale-dependent number parsing is performed.
• Up to 100 violations are collected then checking stops; truncated is true when more violations exist.

Input

• csv (string, required): max length 256000
• columns (array of object, required): max items 256

Output

• valid (boolean, required)
• rows_checked (integer, required)
• truncated (boolean, required)
• violations (array of object, required): max items 100

Limits

• max input bytes: 256000
• max data rows: 5000
• max columns: 256
• max header name bytes: 256
• max violations: 100
• max integer digits: 1000
• max decimal characters: 1000

Example

Request input:

{
  "csv": "id,name,amount,note\n1,Ada,1.5,\n-0,Lin,5.,ok\n",
  "columns": [
    {
      "name": "id",
      "constraint": "integer"
    },
    {
      "name": "name",
      "constraint": "nonempty"
    },
    {
      "name": "amount",
      "constraint": "decimal"
    },
    {
      "name": "note",
      "constraint": "any"
    }
  ]
}

Response:

{
  "result": {
    "valid": true,
    "rows_checked": 2,
    "violations": [],
    "truncated": false
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "csv-schema-check",
  "version": "1.0.0",
  "input": {
    "csv": "id,name,amount,note\n1,Ada,1.5,\n-0,Lin,5.,ok\n",
    "columns": [
      {
        "name": "id",
        "constraint": "integer"
      },
      {
        "name": "name",
        "constraint": "nonempty"
      },
      {
        "name": "amount",
        "constraint": "decimal"
      },
      {
        "name": "note",
        "constraint": "any"
      }
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/csv-schema-check/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"csv":"id,name,amount,note\n1,Ada,1.5,\n-0,Lin,5.,ok\n","columns":[{"name":"id","constraint":"integer"},{"name":"name","constraint":"nonempty"},{"name":"amount","constraint":"decimal"},{"name":"note","constraint":"any"}]}'

The machine-readable contract is at /v1/tools/csv-schema-check/versions/1.0.0.

CLI

node cli.mjs run csv-schema-check 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• CSV split column: Split one CSV column on an exact separator into uniquely named columns.
• CSV abs integer column: Replace every data cell in a named CSV column with the absolute value of a canonical integer.
• CSV clamp integer column: Clamp every data cell in a named CSV column to optional canonical integer min and max bounds.
• CSV dedupe: Remove duplicate CSV data rows while preserving the first occurrence.
• CSV distinct values: List distinct exact values of one CSV column in first-seen order.
• CSV drop columns: Drop named CSV columns and keep the remaining columns in original header order.