jim.com WebMCP audit

Rescan
audited Aug 28, 2026in 8s
61/ 100

2 tools registered. Strongest in WebMCP use, weakest in human experience.

WebMCP use93
Usefulness47
Human experience0
about:blank

No agent run recorded yet.

No steps recorded

Tools

/
calculate_payment_fees: warning

calculate_payment_fees

Exact JIM fee and net payout for a sale. Covers Tap to Pay vs Payment Link, fee pass-through, and JIM Card vs ACH withdrawal. Use instead of estimating.Answers a question. Declared read only.
pagehttps://www.jim.com/
implementation
viaimperative
entry pointdocument
registered after941ms
executepresent
api surface
amount_usdrequired
methodrequired
fee_paid_byoptional
payoutoptional
annotations
read onlytrue
destructivefalse
idempotenttrue
open worldfalse
untrusted contentnot declared
titlenot declared
1 finding
warningHuman parity
0 / 8
2 of 2 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.
calculate_payment_fees, get_pricing
fix
<!-- Give the tool a visible counterpart: a declarative form is one the person can see and use too. -->
<form toolname="calculate_payment_fees" tooldescription="...">
  <!-- the same action, as UI -->
</form>
tool json
{
  "name": "calculate_payment_fees",
  "description": "Exact JIM fee and net payout for a sale. Covers Tap to Pay vs Payment Link, fee pass-through, and JIM Card vs ACH withdrawal. Use instead of estimating.",
  "inputSchema": {
    "type": "object",
    "properties": {
      "amount_usd": {
        "type": "number",
        "description": "Sale amount in USD, before fees."
      },
      "method": {
        "type": "string",
        "enum": [
          "tap_to_pay",
          "payment_link"
        ],
        "description": "Tap to Pay is contactless in person; Payment Link is sent remotely."
      },
      "fee_paid_by": {
        "type": "string",
        "enum": [
          "seller",
          "customer"
        ],
        "description": "Who absorbs the processing fee. Default seller."
      },
      "payout": {
        "type": "string",
        "enum": [
          "jim_card",
          "ach_transfer"
        ],
        "description": "How the seller withdraws. JIM Card is free. Default jim_card."
      }
    },
    "required": [
      "amount_usd",
      "method"
    ],
    "additionalProperties": false
  },
  "annotations": {
    "readOnlyHint": true,
    "destructiveHint": false,
    "idempotentHint": true,
    "openWorldHint": false
  }
}
Showing calculate_payment_fees

Findings

WebMCP use

93 / 100 · weight 50
passTools registered
4 / 4
2 tools registered across 1 page.
passReal-browser eligible
8 / 8
A real browser exposes modelContext natively on this page, so the tools registered here are visible to an agent today.
passRegistration timing
4 / 4
Every measured tool registered within 941.5ms of navigation.
toolget_pricing
passCanonical entry point
4 / 4
All 2 tools register on the canonical document.modelContext entry point.
passSchema validity
5 / 5
All 2 tools declare a structurally valid object input schema.
warningSchema quality
2 / 4
1 of 2 tool schemas are harder for an agent to use than they need to be: get_pricing declares no required list, so an agent cannot tell which parameters are mandatory.
toolget_pricing
get_pricing: declares no required list, so an agent cannot tell which parameters are mandatory
fix
{
  name: "get_pricing",
  inputSchema: {
    type: "object",
    properties: {
      query: { type: "string", description: "What to search for" }
    },
    required: ["query"]
  }
}
passStub detection
5 / 5
All 2 tools declare an execute handler.
passAnnotations present
4 / 4
All 2 tools declare a readOnlyHint, so an agent knows which calls change state.
passAnnotation mismatch
3 / 3
No tool claims to be read-only while its name says it writes (2 declared hints checked).
not applicableUntrusted content hint
0 / 2
No tool's contract suggests it returns text written by somebody other than the site, so there is nothing to flag as untrusted.
passRegistration errors
2 / 2
No tool registration threw during the capture.
warningToolchange coherence
1 / 2
2 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

47 / 100 · weight 30
passNaming quality
2 / 2
All 2 tool names are consistent, verb-led, and within Chrome's size guidance.
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.
failCoverage vs. site type
2.7 / 8
The tool set covers 1 of the 3 things an agent needs on a finance site; it cannot read a balance or position or list transactions or activity.

Human experience

0 / 100 · weight 20
warningHuman parity
0 / 8
2 of 2 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.
toolcalculate_payment_fees
calculate_payment_fees, get_pricing
fix
<!-- Give the tool a visible counterpart: a declarative form is one the person can see and use too. -->
<form toolname="calculate_payment_fees" 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
2
run time
8s
finished
Aug 28, 2026