diff --git a/README.md b/README.md
index 59a5921..986a218 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,8 @@ tag, or opt-in to [use a full Git commit SHA] and Dependabot.
 
 ### Trusted publishing
 
-> **NOTE**: Trusted publishing is sometimes referred to by its
+> [!NOTE]
+> Trusted publishing is sometimes referred to by its
 > underlying technology -- OpenID Connect, or OIDC for short.
 > If you see references to "OIDC publishing" in the context of PyPI,
 > this is what they're referring to.
@@ -61,10 +62,11 @@ jobs:
       uses: pypa/gh-action-pypi-publish@release/v1
 ```
 
-> **Pro tip**: instead of using branch pointers, like `unstable/v1`, pin
-versions of Actions that you use to tagged versions or sha1 commit identifiers.
-This will make your workflows more secure and better reproducible, saving you
-from sudden and unpleasant surprises.
+> [!NOTE]
+> Pro tip: instead of using branch pointers, like `unstable/v1`, pin versions of
+> Actions that you use to tagged versions or sha1 commit identifiers.
+> This will make your workflows more secure and better reproducible, saving you
+> from sudden and unpleasant surprises.
 
 Other indices that support trusted publishing can also be used, like TestPyPI:
 
@@ -76,7 +78,8 @@ Other indices that support trusted publishing can also be used, like TestPyPI:
 ```
 _(don't forget to update the environment name to `testpypi` or similar!)_
 
-> **Pro tip**: only set the `id-token: write` permission in the job that does
+> [!NOTE]
+> Pro tip: only set the `id-token: write` permission in the job that does
 > publishing, not globally. Also, try to separate building from publishing
 > — this makes sure that any scripts maliciously injected into the build
 > or test environment won't be able to elevate privileges while flying under
@@ -96,7 +99,8 @@ This GitHub Action [has nothing to do with _building package
 distributions_]. Users are responsible for preparing dists for upload
 by putting them into the `dist/` folder prior to running this Action.
 
-> **IMPORTANT**: Since this GitHub Action is docker-based, it can only
+> [!IMPORTANT]
+> Since this GitHub Action is docker-based, it can only
 > be used from within GNU/Linux based jobs in GitHub Actions CI/CD
 > workflows. This is by design and is unlikely to change due to a number
 > of considerations we rely on.
@@ -187,9 +191,10 @@ default) setting as follows:
      skip-existing: true
 ```
 
-> **Pro tip**: try to avoid enabling this setting where possible. If you
-have steps for publishing to both PyPI and TestPyPI, consider only using
-it for the latter, having the former fail loudly on duplicates.
+> [!NOTE]
+> Pro tip: try to avoid enabling this setting where possible. If you
+> have steps for publishing to both PyPI and TestPyPI, consider only using
+> it for the latter, having the former fail loudly on duplicates.
 
 ### For Debugging
 
diff --git a/oidc-exchange.py b/oidc-exchange.py
index cc625d3..671c034 100644
--- a/oidc-exchange.py
+++ b/oidc-exchange.py
@@ -1,3 +1,5 @@
+import base64
+import json
 import os
 import sys
 from http import HTTPStatus
@@ -50,6 +52,25 @@
 Token request failed: the server refused the request for the following reasons:
 
 {reasons}
+
+This generally indicates a trusted publisher configuration error, but could
+also indicate an internal error on GitHub or PyPI's part.
+
+{rendered_claims}
+"""
+
+_RENDERED_CLAIMS = """
+The claims rendered below are **for debugging purposes only**. You should **not**
+use them to configure a trusted publisher unless they already match your expectations.
+
+If a claim is not present in the claim set, then it is rendered as `MISSING`.
+
+* `sub`: `{sub}`
+* `repository`: `{repository}`
+* `repository_owner`: `{repository_owner}`
+* `repository_owner_id`: `{repository_owner_id}`
+* `job_workflow_ref`: `{job_workflow_ref}`
+* `ref`: `{ref}`
 """
 
 # Rendered if the package index's token response isn't valid JSON.
@@ -121,6 +142,23 @@ def assert_successful_audience_call(resp: requests.Response, domain: str):
             )
 
 
+def render_claims(token: str) -> str:
+    _, payload, _ = token.split(".", 2)
+    claims = json.loads(base64.urlsafe_b64decode(payload))
+
+    def _get(name: str) -> str:  # noqa: WPS430
+        return claims.get(name, "MISSING")
+
+    return _RENDERED_CLAIMS.format(
+        sub=_get("sub"),
+        repository=_get("repository"),
+        repository_owner=_get("repository_owner"),
+        repository_owner_id=_get("repository_owner_id"),
+        job_workflow_ref=_get("job_workflow_ref"),
+        ref=_get("ref"),
+    )
+
+
 repository_url = get_normalized_input("repository-url")
 repository_domain = urlparse(repository_url).netloc
 token_exchange_url = f"https://{repository_domain}/_/oidc/github/mint-token"
@@ -165,7 +203,13 @@ def assert_successful_audience_call(resp: requests.Response, domain: str):
         for error in mint_token_payload["errors"]
     )
 
-    die(_SERVER_REFUSED_TOKEN_EXCHANGE_MESSAGE.format(reasons=reasons))
+    rendered_claims = render_claims(oidc_token)
+
+    die(
+        _SERVER_REFUSED_TOKEN_EXCHANGE_MESSAGE.format(
+            reasons=reasons, rendered_claims=rendered_claims,
+        ),
+    )
 
 pypi_token = mint_token_payload.get("token")
 if pypi_token is None:
diff --git a/requirements/runtime.txt b/requirements/runtime.txt
index b3f1337..c795e84 100644
--- a/requirements/runtime.txt
+++ b/requirements/runtime.txt
@@ -14,7 +14,7 @@ cffi==1.15.1
     # via cryptography
 charset-normalizer==3.2.0
     # via requests
-cryptography==41.0.2
+cryptography==41.0.3
     # via secretstorage
 docutils==0.20.1
     # via readme-renderer