peppolvalidator.com WebMCP audit

Name: peppolvalidator.com WebMCP audit
Creator: ora

Rescan

audited Aug 28, 2026in 5s

59/ 100

4 tools registered. Strongest in usefulness, weakest in human experience.

WebMCP use66

Usefulness88

Human experience0

about:blank

No agent run recorded yet.

No steps recorded

Tools

validate_invoice

Validate a Peppol UBL 2.1 or CII XML invoice against EN16931 (CEN) and Peppol BIS Billing 3.0 schematron rules. Returns validation status, errors, warnings, and a shareable results URL.Answers a question. Declared read only.

pagehttps://peppolvalidator.com/

implementation

viaimperative

entry pointnavigator

registered after272ms

executepresent

api surface

xmlrequired

annotations

read onlytrue

destructivenot declared

idempotentnot declared

open worldnot declared

untrusted contentnot declared

titlenot declared

2 findings

failCanonical entry point

0 / 4

Every tool registers through the deprecated navigator.modelContext alias; move them to document.modelContext before the alias is removed.

fix

// Use the canonical entry point - navigator.modelContext is deprecated.
document.modelContext.provideContext({ tools: [/* ... */] });

warningHuman parity

0 / 8

4 of 4 tools run through the JavaScript API with no visible counterpart, so the person co-browsing cannot see what the agent is offered. Declarative forms (or at least a title annotation) close the gap.

validate_invoice, convert_xml_to_pdf, get_verification_challenge, submit_feedback

fix

<!-- Give the tool a visible counterpart: a declarative form is one the person can see and use too. -->
<form toolname="validate_invoice" tooldescription="...">
  <!-- the same action, as UI -->
</form>

tool json

{
  "name": "validate_invoice",
  "description": "Validate a Peppol UBL 2.1 or CII XML invoice against EN16931 (CEN) and Peppol BIS Billing 3.0 schematron rules. Returns validation status, errors, warnings, and a shareable results URL.",
  "inputSchema": {
    "type": "object",
    "properties": {
      "xml": {
        "type": "string",
        "description": "The raw XML content of the invoice to validate"
      }
    },
    "required": [
      "xml"
    ]
  },
  "annotations": {
    "readOnlyHint": true
  }
}

Findings

WebMCP use

66 / 100 · weight 50

passTools registered

4 / 4

4 tools registered across 1 page.

failReal-browser eligible

0 / 8

The page's code registers these tools, but a real visitor's browser does not get them yet: WebMCP needs a native modelContext or a current origin trial token, and this page has neither.

passRegistration timing

4 / 4

Every measured tool registered within 271.90000009536743ms of navigation.

toolsubmit_feedback

failCanonical entry point

0 / 4

Every tool registers through the deprecated navigator.modelContext alias; move them to document.modelContext before the alias is removed.

toolvalidate_invoice

fix

// Use the canonical entry point - navigator.modelContext is deprecated.
document.modelContext.provideContext({ tools: [/* ... */] });

passSchema validity

5 / 5

All 4 tools declare a structurally valid object input schema.

passSchema quality

4 / 4

All 4 tool schemas describe their parameters and stay within Chrome's size guidance.

passStub detection

5 / 5

All 4 tools declare an execute handler.

warningAnnotations present

3 / 4

1 of 4 tools declare no readOnlyHint, so an agent cannot tell a read from a write without guessing from the name.

toolsubmit_feedback

submit_feedback

fix

{
  name: "submit_feedback",
  annotations: { readOnlyHint: true, destructiveHint: false, idempotentHint: true }
}

passAnnotation mismatch

3 / 3

No tool claims to be read-only while its name says it writes (3 declared hints checked).

warningUntrusted content hint

0 / 2

1 of 1 tools look like they return text written by other people but declare no untrustedContentHint, so an agent will treat the response as the site speaking.

toolsubmit_feedback

submit_feedback: feedback, issue

fix

{ name: "submit_feedback", annotations: { untrustedContentHint: true } }

passRegistration errors

2 / 2

No tool registration threw during the capture.

warningToolchange coherence

1 / 2

4 tools were registered but the page never dispatched a toolchange event, so an agent subscribed to registry updates never learns they exist.

fix

document.modelContext.dispatchEvent(new Event("toolchange"));

not applicableInjection surface

0 / 3

The injection-surface model hop returned no usable result, so tool contracts were not reviewed for injection surface.

Usefulness

88 / 100 · weight 30

warningNaming quality

1.8 / 2

Tool naming makes selection harder than it needs to be: 1 name does not start with a verb (convert_xml_to_pdf).

toolconvert_xml_to_pdf

fix

{ name: "convert_xml_to_pdf" /* short, unique, verb-based */ }

not applicableDescription quality

0 / 6

The description-quality model hop returned no usable result, so descriptions were not rated.

not applicableTool selection

0 / 14

The tool-selection model hop returned no usable result.

not applicableCoverage vs. site type

0 / 8

This tool set does not place the site in a category with a known expected tool shape, so there is no coverage baseline to score it against.

Human experience

0 / 100 · weight 20

warningHuman parity

0 / 8

toolvalidate_invoice

validate_invoice, convert_xml_to_pdf, get_verification_challenge, submit_feedback

fix

<!-- Give the tool a visible counterpart: a declarative form is one the person can see and use too. -->
<form toolname="validate_invoice" tooldescription="...">
  <!-- the same action, as UI -->
</form>

not applicablePage experience

0 / 12

The page-experience model hop returned no usable result, so the page was not graded.

Tool selection

The tool-selection model hop returned no usable result.

how this was captured

chrome: 148.0.7778.96
capture shim: v1
spec snapshot: 2026-08
mode: fast
pages: 1
tools: 4
run time: 5s
finished: Aug 28, 2026