# Xpath10 evaluate

`xpath10-evaluate` · version 1.0.0 · Structured formats · free, no key needed

Evaluate an XPath 1.0 value expression and return its type with an exact string, number, or boolean token.

**Use when you need to: evaluate an xpath 1.0 value expression · xpath 1.0 expression result type · xpath core functions without a document.**

## Decide before calling

Read the [versioned contract](/v1/tools/xpath10-evaluate/versions/1.0.0) and the supported scope below. Reuse `xpath10-evaluate@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 `xpath10-evaluate@1.0.0` for evaluate an xpath 1.0 value expression. 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

- evaluate an xpath 1.0 value expression
- xpath 1.0 expression result type
- xpath core functions without a document
- tagged xpath 1.0 string number or boolean
- compute an xpath 1.0 expression value
- xpath literals operators and core functions
- xpath 1.0 value subset result
- חישוב xpath evaluate

## Not supported

- select XML nodes
- bind XPath variables
- evaluate XPath 2.0 or XQuery

## Behavior

- Evaluates one XPath 1.0 value expression and returns type string, number, or boolean. result is always a string token: the string itself, the numeric token (-0 for negative zero), or true or false. xpath_string is the section 4.2 conversion. Negative zero's xpath_string is 0.
- The same expression subset, conversions, short-circuit, and rejections as the typed tools. This tool accepts every result type the subset can produce.
- Keyword operators match only token kind name. Symbolic operators and parentheses match only kind op. Quoted operator spellings are syntax errors.
- Key order is type, result, xpath_string. A string result of 86 code points produces 219 UTF-8 bytes of JSON, the output cap. 87 code points is limit_exceeded.
- Check order: input bytes, parse limits and unsupported syntax, the 96-character string cap, then output bytes. There is no result_type rejection.
- / is not division. Node-sets, variables, predicates, axes, namespaces, and XPath 2.0 are rejected by name rather than approximated.

## Input

- `expression` (string, required): min length 1; max length 512; XPath 1.0 value expression. maxLength counts Unicode code points. The UTF-8 cap is limits.max_input_bytes.

## Output

- `type` (one of "string", "number", "boolean", required)
- `result` (string, required): max length 96; String value, numeric token (negative zero is -0), or true or false. Empty is allowed for a string.
- `xpath_string` (string, required): max length 96; Section 4.2 conversion. Negative zero is 0. Booleans are true or false.

## Limits

- max input bytes: 512
- max string codepoints: 96
- max depth: 8
- max nodes: 21
- max arguments: 4
- max output bytes: 219

## Example

Request input:

```json
{
  "expression": "substring(\"12345\",2,3)"
}
```

Response:

```json
{
  "result": {
    "type": "string",
    "result": "234",
    "xpath_string": "234"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "xpath10-evaluate",
  "version": "1.0.0",
  "input": {
    "expression": "substring(\"12345\",2,3)"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/xpath10-evaluate/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"expression":"substring(\"12345\",2,3)"}'
```

The machine-readable contract is at [/v1/tools/xpath10-evaluate/versions/1.0.0](/v1/tools/xpath10-evaluate/versions/1.0.0).

### CLI

```sh
node cli.mjs run xpath10-evaluate 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [Xpath10 boolean](/tools/xpath10-boolean): Evaluate an XPath 1.0 boolean expression: comparisons, and, or, not, starts-with, contains, and boolean conversion.
- [Xpath10 number](/tools/xpath10-number): Evaluate an XPath 1.0 numeric expression: arithmetic, div, mod, floor, ceiling, round, and number conversion.
- [Xpath10 string](/tools/xpath10-string): Evaluate an XPath 1.0 expression that yields a string, including concat, substring, translate, and string conversion.
- [Xpath10 count](/tools/xpath10-count): Count the nodes in an XPath 1.0 node-set from location paths, axes, predicates, namespaces and union.
- [Xpath10 paths](/tools/xpath10-paths): List the canonical XPath 1.0 path of each node in a location-path node-set, in document order.
- [Xpath10 select](/tools/xpath10-select): Select an XPath 1.0 node-set from location paths, axes, predicates, namespaces and union, in document order.