Text slice codepoints

text-slice-codepoints · version 1.0.0 · Text · free, no key needed

Slice a string by Unicode code-point indexes, not UTF-16 code units.

Use when you need to: text slice codepoints · slice text by unicode code points · code point substring.

Decide before calling

Read the versioned contract and the supported scope below. Reuse text-slice-codepoints@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use text-slice-codepoints@1.0.0 for text slice codepoints. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• text slice codepoints
• slice text by unicode code points
• code point substring

Not supported

• UTF-16 code-unit slicing
• grapheme cluster slicing
• negative indexes
• python wrap-around slicing
• byte-offset slicing
• read files

Behavior

• text is a UTF-8 bounded string of at most 250 KiB.
• start and length are JSON integers >= 0. Negative indexes and wrap-around are rejected.
• Indexes count Unicode code points as in Array.from(text), not UTF-16 units and not grapheme clusters.
• If start is greater than the code-point count, or start + length is greater than the code-point count, the tool throws slice out of range.
• A zero-length slice at start equal to the code-point count is allowed and returns an empty string.
• No Unicode normalization or case folding is applied.

Input

• text (string, required): max length 256000
• start (integer, required): min 0
• length (integer, required): min 0

Output

• text (string, required): max length 256000

Limits

• max text bytes: 256000

Example

Request input:

{
  "text": "hello",
  "start": 1,
  "length": 3
}

Response:

{
  "result": {
    "text": "ell"
  }
}

How to call it

MCP

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

{
  "id": "text-slice-codepoints",
  "version": "1.0.0",
  "input": {
    "text": "hello",
    "start": 1,
    "length": 3
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/text-slice-codepoints/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"text":"hello","start":1,"length":3}'

The machine-readable contract is at /v1/tools/text-slice-codepoints/versions/1.0.0.

CLI

node cli.mjs run text-slice-codepoints 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Text wrap width: Hard-wrap text by Unicode code-point width and return the resulting lines.
• Citation anchor check: Check a quote anchor (exact text plus prefix/suffix) matches exactly one place in a supplied source version.
• Text count: Count Unicode code points, UTF-16 code units, UTF-8 bytes, and lines.
• Text levenshtein distance: Compute bounded Levenshtein distance over code points or deterministic grapheme tokens.
• Text run length decode: Decode canonical count:HEX; run-length text and return the expanded Unicode string.
• Text sentence offsets: Return UAX #29 sentence spans as start/end offsets in code points, UTF-16 units or UTF-8 bytes, with the ending rule.