docs: clarify ChatGPT Site tools compatibility

CHANGELOG.md

@@ -19,6 +19,8 @@ reconstruct them from git history.
 - Split deterministic WebMCP smoke verification from probabilistic tool-selection
   and journey evals, added trajectory-led failure diagnosis for `webmcp-evals`
   0.0.4, and dated Puppeteer's Chrome 151+ harness requirement.
+- Documented ChatGPT Site tools' current top-level imperative-only compatibility
+  boundary separately from the broader WebMCP APIs verified in Chrome.
 
 ## [0.4.0] — 2026-08-17
 

release/v0.5.0.md

@@ -28,8 +28,11 @@ The rest of the pipeline is stricter where real integrations failed:
   Chrome profile and a real headed browser environment.
 
 The skill also documents ChatGPT's **Site tools** surface separately from Chrome
-developer verification. Availability details are dated 2026-08-27 and link to the
-official OpenAI documentation because model/workspace support can change.
+developer verification. Availability details are dated 2026-08-31 and link to the
+official OpenAI documentation because model/workspace support can change. ChatGPT's
+built-in browser currently discovers top-level imperative tools, not declarative
+forms or iframe registrations; that client subset is separate from Chrome's broader
+WebMCP implementation.
 
 Compatibility note: no public source or measured client run establishes a universal
 safe tool count per page. Parity is an auditable coverage target, not a promise that

skills/webmcpify/references/client.md

@@ -1,6 +1,6 @@
 # ChatGPT client reality — Site tools
 
-Checked 2026-08-27 against the official OpenAI documentation:
+Checked 2026-08-31 against the official OpenAI documentation:
 <https://learn.chatgpt.com/docs/webmcp>. Re-check that page before publishing or
 relying on model/workspace availability; this UI is moving independently of the
 WebMCP draft and Chrome implementation.
@@ -16,6 +16,11 @@ WebMCP draft and Chrome implementation.
   current, and availability still depends on rollout and the current page.
 - The official page says Site tools are unavailable in Enterprise and Edu
   workspaces.
+- ChatGPT's built-in browser currently implements only a subset of WebMCP: it
+  discovers imperative tools registered with JavaScript in the top-level page,
+  not declarative form tools or tools registered inside iframes. This is a
+  client compatibility boundary, not evidence that either broader WebMCP form
+  or frame support is invalid in Chrome.
 - Tools belong to the page that registered them. Closing or navigating away can
   make them unavailable; a client that tears down the page between turns cannot
   call that old registration.
@@ -42,6 +47,9 @@ customer report or publishing a claim.
 3. Confirm the account/workspace is eligible; absence on the wrong model can look
    exactly like a broken integration because the assistant falls back to ordinary
    browser interaction.
-4. For the website itself, confirm a secure context and live registration. Use the
+4. Confirm the expected Site tool is registered imperatively in the top-level
+   page. A declarative form or iframe registration may be valid WebMCP but is not
+   currently discoverable as a ChatGPT Site tool.
+5. For the website itself, confirm a secure context and live registration. Use the
    headed-Chrome harness in `verify.md` for developer proof; ChatGPT availability
    and Chrome harness success are separate checks.

skills/webmcpify/references/verify.md

@@ -118,9 +118,9 @@ tooling ignores `NODE_PATH`, symlink instead:
 a standalone harness.
 
 For ChatGPT's separate built-in-browser experience—named **Site tools**, with
-account/model availability and page-lifetime behavior—use `references/client.md`.
-Chrome harness success alone does not prove a specific ChatGPT account can use the
-tools.
+account/model availability, a narrower API subset, and page-lifetime behavior—use
+`references/client.md`. Chrome harness success alone does not prove a specific
+ChatGPT account can use every verified tool.
 
 **Alternative:** Puppeteer ships a first-class experimental WebMCP API
 (https://pptr.dev/guides/webmcp) — prefer it when the target repo already uses