diff --git a/action.yml b/action.yml
index 7b2b3cb1..eb102b18 100644
--- a/action.yml
+++ b/action.yml
@@ -100,21 +100,21 @@ runs:
         if [[ $flag && ${{ github.event.action }} != 'deleted' ]]; then
           if [ $bot_comment_id ]; then
             if [[ $type = pr_comment ]] || [[ $type = pr_description ]]; then
-              gh api repos/${{ github.repository }}/issues/comments/$bot_comment_id -X PATCH -f body="$message"
+              postCommentWithFallback "$message" gh api repos/${{ github.repository }}/issues/comments/$bot_comment_id -X PATCH -f body="$message"
             elif [[ $type = issue_comment ]] || [[ $type = issue_description ]]; then
-              gh api repos/${{ github.repository }}/issues/comments/$bot_comment_id -X PATCH -f body="$message"
+              postCommentWithFallback "$message" gh api repos/${{ github.repository }}/issues/comments/$bot_comment_id -X PATCH -f body="$message"
             elif [[ $type = discussion_description ]] || [[ $type = discussion_comment ]]; then
-              gh api graphql -f  query='mutation($commentId: ID!, $body: String!) { updateDiscussionComment(input: {commentId: $commentId, body: $body}) { comment { id body }}}' -f commentId=$bot_comment_id -f body="$message"
+              postCommentWithFallback "$message" gh api graphql -f  query='mutation($commentId: ID!, $body: String!) { updateDiscussionComment(input: {commentId: $commentId, body: $body}) { comment { id body }}}' -f commentId=$bot_comment_id -f body="$message"
             fi
           else 
             if [[ $type = pr_comment ]] || [[ $type = pr_description ]]; then
-              gh pr comment $issue_url --body "$message"
+              postCommentWithFallback "$message" gh pr comment $issue_url --body "$message"
             elif [[ $type = issue_comment ]] || [[ $type = issue_description ]]; then
-              gh issue comment $issue_url --body "$message"
+              postCommentWithFallback "$message" gh issue comment $issue_url --body "$message"
             elif [[ $type = discussion_description ]]; then
-              addDiscussionComment $discussion_node_id "$message"
+              postCommentWithFallback "$message" addDiscussionComment $discussion_node_id "$message"
             elif [[ $type = discussion_comment ]]; then
-              addDiscussionComment $discussion_node_id "$message" $reply_to_id 
+              postCommentWithFallback "$message" addDiscussionComment $discussion_node_id "$message" $reply_to_id
             fi
           fi
         else 
diff --git a/queries.sh b/queries.sh
index bd6b7d02..f5d50c22 100644
--- a/queries.sh
+++ b/queries.sh
@@ -1,5 +1,42 @@
 #!/bin/bash
 
+# Runs a comment command and falls back to the log and job summary when a fork token cannot write comments.
+function postCommentWithFallback() {
+  local MESSAGE=$1
+  shift
+
+  local OUTPUT
+  local EXIT_CODE
+
+  if OUTPUT=$("$@" 2>&1); then
+    if [ -n "$OUTPUT" ]; then
+      printf '%s\n' "$OUTPUT"
+    fi
+    return 0
+  else
+    EXIT_CODE=$?
+  fi
+
+  if [[ "$OUTPUT" == *"Resource not accessible by integration"* ]]; then
+    printf '%s\n' "::warning::Unable to post the accessibility alt text comment because the workflow token cannot write comments. The message is included below and in the job summary."
+    printf '\n%s\n' "$MESSAGE"
+
+    if [ -n "${GITHUB_STEP_SUMMARY:-}" ]; then
+      {
+        printf '# Accessibility alt text bot\n\n'
+        printf '%s\n' "$MESSAGE"
+      } >> "$GITHUB_STEP_SUMMARY"
+    fi
+
+    return 0
+  fi
+
+  if [ -n "$OUTPUT" ]; then
+    printf '%s\n' "$OUTPUT" >&2
+  fi
+  return "$EXIT_CODE"
+}
+
 # Given a node_id for a discussion comment that is a reply in thread, return the parent comment's node ID.
 function getDiscussionReplyToId() {
   local NODE_ID=$1
@@ -33,7 +70,7 @@ function addDiscussionComment() {
       }
     '
   else
-    gh api graphql -F discussionId="$discussion_node_id" -F body="$message" -f query='
+    gh api graphql -F discussionId="$DISCUSSION_NODE_ID" -F body="$MESSAGE" -f query='
       mutation($discussionId: ID!, $body: String!) {
         addDiscussionComment(input: {discussionId: $discussionId, body: $body}) {
           comment {
diff --git a/src/queries.test.js b/src/queries.test.js
new file mode 100644
index 00000000..cefbfb96
--- /dev/null
+++ b/src/queries.test.js
@@ -0,0 +1,116 @@
+import { spawnSync } from "node:child_process";
+import {
+  existsSync,
+  mkdtempSync,
+  readFileSync,
+  rmSync,
+} from "node:fs";
+import { tmpdir } from "node:os";
+import { dirname, join } from "node:path";
+import { fileURLToPath } from "node:url";
+
+import { describe, expect, test } from "vitest";
+
+const queriesPath = join(
+  dirname(fileURLToPath(import.meta.url)),
+  "..",
+  "queries.sh",
+);
+
+const runShell = (body) => {
+  const temporaryDirectory = mkdtempSync(
+    join(tmpdir(), "accessibility-alt-text-bot-"),
+  );
+  const summaryPath = join(temporaryDirectory, "summary.md");
+
+  try {
+    const result = spawnSync(
+      "bash",
+      [
+        "-c",
+        `set -e -o pipefail\nsource "$1"\n${body}`,
+        "queries-test",
+        queriesPath,
+      ],
+      {
+        encoding: "utf8",
+        env: {
+          ...process.env,
+          GITHUB_STEP_SUMMARY: summaryPath,
+          TEST_MESSAGE: "Complete fallback message\nwith a second line.",
+        },
+      },
+    );
+
+    return {
+      result,
+      summary: existsSync(summaryPath)
+        ? readFileSync(summaryPath, "utf8")
+        : undefined,
+    };
+  } finally {
+    rmSync(temporaryDirectory, { recursive: true, force: true });
+  }
+};
+
+describe("postCommentWithFallback", () => {
+  test("preserves successful command output without a fallback", () => {
+    const { result, summary } = runShell(`
+      postCommentWithFallback "$TEST_MESSAGE" bash -c \
+        'printf "%s\\n" "$1"' comment-command "$TEST_MESSAGE"
+    `);
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toBe("Complete fallback message\nwith a second line.\n");
+    expect(result.stderr).toBe("");
+    expect(summary).toBeUndefined();
+  });
+
+  test("reports the full message when fork permissions prevent a comment", () => {
+    const { result, summary } = runShell(`
+      postCommentWithFallback "$TEST_MESSAGE" bash -c \
+        'printf "GraphQL: Resource not accessible by integration (addComment)\\n" >&2; exit 1'
+    `);
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain(
+      "::warning::Unable to post the accessibility alt text comment",
+    );
+    expect(result.stdout).toContain("Complete fallback message\nwith a second line.");
+    expect(result.stderr).toBe("");
+    expect(summary).toContain("# Accessibility alt text bot");
+    expect(summary).toContain("Complete fallback message\nwith a second line.");
+  });
+
+  test("preserves unexpected failures", () => {
+    const { result, summary } = runShell(`
+      postCommentWithFallback "$TEST_MESSAGE" bash -c \
+        'printf "unexpected API failure\\n" >&2; exit 23'
+    `);
+
+    expect(result.status).toBe(23);
+    expect(result.stdout).toBe("");
+    expect(result.stderr).toBe("unexpected API failure\n");
+    expect(summary).toBeUndefined();
+  });
+});
+
+describe("addDiscussionComment", () => {
+  test("uses its explicit arguments for a top-level comment", () => {
+    const { result } = runShell(`
+      discussion_node_id="global-id"
+      message="global message"
+      gh() { printf '<%s>\\n' "$@"; }
+
+      addDiscussionComment "argument-id" "$TEST_MESSAGE"
+    `);
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain("<discussionId=argument-id>");
+    expect(result.stdout).toContain(
+      "<body=Complete fallback message\nwith a second line.>",
+    );
+    expect(result.stdout).not.toContain("global-id");
+    expect(result.stdout).not.toContain("global message");
+  });
+});