primitive.dev WebMCP audit

Rescan
audited Aug 28, 2026in 7s
45/ 100

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

WebMCP use60
Usefulness50
Human experience0
about:blank

No agent run recorded yet.

No steps recorded

Tools

/
primitive_overview: fail

primitive_overview

Explain what Primitive is (email infrastructure for AI agents) and return the machine-readable entry points an agent should use to integrate: MCP endpoint, OpenAPI spec, CLI, llms.txt, and OAuth metadata.Takes an action on the site.
pagehttps://www.primitive.dev/
implementation
viaimperative
entry pointnavigator
registered after612ms
executepresent
api surfaceTakes no parameters.
annotations
read onlynot declared
destructivenot declared
idempotentnot declared
open worldnot declared
untrusted contentnot declared
titlenot declared
4 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: [/* ... */] });
warningNaming quality
1 / 2
Tool naming makes selection harder than it needs to be: 2 names do not start with a verb (primitive_overview).
fix
{ name: "primitive_overview" /* short, unique, verb-based */ }
failAnnotations present
0 / 4
2 of 2 tools declare no readOnlyHint, so an agent cannot tell a read from a write without guessing from the name.
primitive_overview, primitive_quickstart
fix
{
  name: "primitive_overview",
  annotations: { readOnlyHint: true, destructiveHint: false, idempotentHint: true }
}
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.
primitive_overview, primitive_quickstart
fix
<!-- Give the tool a visible counterpart: a declarative form is one the person can see and use too. -->
<form toolname="primitive_overview" tooldescription="...">
  <!-- the same action, as UI -->
</form>
tool json
{
  "name": "primitive_overview",
  "description": "Explain what Primitive is (email infrastructure for AI agents) and return the machine-readable entry points an agent should use to integrate: MCP endpoint, OpenAPI spec, CLI, llms.txt, and OAuth metadata.",
  "inputSchema": {
    "type": "object",
    "properties": {},
    "additionalProperties": false
  },
  "annotations": {}
}
Showing primitive_overview

Findings

WebMCP use

60 / 100 · weight 50
passTools registered
4 / 4
2 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 612.1999998092651ms of navigation.
toolprimitive_quickstart
failCanonical entry point
0 / 4
Every tool registers through the deprecated navigator.modelContext alias; move them to document.modelContext before the alias is removed.
toolprimitive_overview
fix
// Use the canonical entry point - navigator.modelContext is deprecated.
document.modelContext.provideContext({ tools: [/* ... */] });
passSchema validity
5 / 5
All 2 tools declare a structurally valid object input schema.
passSchema quality
4 / 4
All 2 tool schemas describe their parameters and stay within Chrome's size guidance.
passStub detection
5 / 5
All 2 tools declare an execute handler.
failAnnotations present
0 / 4
2 of 2 tools declare no readOnlyHint, so an agent cannot tell a read from a write without guessing from the name.
toolprimitive_overview
primitive_overview, primitive_quickstart
fix
{
  name: "primitive_overview",
  annotations: { readOnlyHint: true, destructiveHint: false, idempotentHint: true }
}
not applicableAnnotation mismatch
0 / 3
No tool declares a readOnlyHint, so there is no safety claim to contradict.
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

50 / 100 · weight 30
warningNaming quality
1 / 2
Tool naming makes selection harder than it needs to be: 2 names do not start with a verb (primitive_overview).
toolprimitive_overview
fix
{ name: "primitive_overview" /* 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
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.
toolprimitive_overview
primitive_overview, primitive_quickstart
fix
<!-- Give the tool a visible counterpart: a declarative form is one the person can see and use too. -->
<form toolname="primitive_overview" 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
7s
finished
Aug 28, 2026