Add MCP tool for replying to posts

mcp/src/openisle_mcp/server.py

@@ -12,6 +12,7 @@ from pydantic import Field as PydanticField
 
 from .config import get_settings
 from .schemas import (
+    CommentCreateResult,
     CommentData,
     CommentReplyResult,
     PostDetail,
@@ -41,9 +42,9 @@ async def lifespan(_: FastMCP):
 app = FastMCP(
     name="openisle-mcp",
     instructions=(
-        "Use this server to search OpenIsle content, reply to comments with an authentication "
-        "token, retrieve details for a specific post, and list posts created within a recent time "
-        "window."
+        "Use this server to search OpenIsle content, reply to posts and comments with an "
+        "authentication token, retrieve details for a specific post, and list posts created "
+        "within a recent time window."
     ),
     host=settings.host,
     port=settings.port,
@@ -96,6 +97,100 @@ async def search(
     return SearchResponse(keyword=sanitized, total=len(results), results=results)
 
 
+@app.tool(
+    name="reply_to_post",
+    description="Create a comment on a post using an authentication token.",
+    structured_output=True,
+)
+async def reply_to_post(
+    post_id: Annotated[
+        int,
+        PydanticField(ge=1, description="Identifier of the post being replied to."),
+    ],
+    token: Annotated[
+        str,
+        PydanticField(description="JWT bearer token for the user performing the reply."),
+    ],
+    content: Annotated[
+        str,
+        PydanticField(description="Markdown content of the reply."),
+    ],
+    captcha: Annotated[
+        str | None,
+        PydanticField(
+            default=None,
+            description="Optional captcha solution if the backend requires it.",
+        ),
+    ] = None,
+    ctx: Context | None = None,
+) -> CommentCreateResult:
+    """Create a comment on a post and return the backend payload."""
+
+    sanitized_content = content.strip()
+    if not sanitized_content:
+        raise ValueError("Reply content must not be empty.")
+
+    sanitized_token = token.strip()
+    if not sanitized_token:
+        raise ValueError("Authentication token must not be empty.")
+
+    sanitized_captcha = captcha.strip() if isinstance(captcha, str) else None
+
+    try:
+        raw_comment = await search_client.reply_to_post(
+            post_id,
+            sanitized_token,
+            sanitized_content,
+            sanitized_captcha,
+        )
+    except httpx.HTTPStatusError as exc:  # pragma: no cover - network errors
+        status_code = exc.response.status_code
+        if status_code == 401:
+            message = (
+                "Authentication failed while replying to post "
+                f"{post_id}. Please verify the token."
+            )
+        elif status_code == 403:
+            message = (
+                "The provided token is not authorized to reply to post "
+                f"{post_id}."
+            )
+        elif status_code == 404:
+            message = f"Post {post_id} was not found."
+        else:
+            message = (
+                "OpenIsle backend returned HTTP "
+                f"{status_code} while replying to post {post_id}."
+            )
+        if ctx is not None:
+            await ctx.error(message)
+        raise ValueError(message) from exc
+    except httpx.RequestError as exc:  # pragma: no cover - network errors
+        message = (
+            "Unable to reach OpenIsle backend comment service: "
+            f"{exc}."
+        )
+        if ctx is not None:
+            await ctx.error(message)
+        raise ValueError(message) from exc
+
+    try:
+        comment = CommentData.model_validate(raw_comment)
+    except ValidationError as exc:
+        message = "Received malformed data from the post comment endpoint."
+        if ctx is not None:
+            await ctx.error(message)
+        raise ValueError(message) from exc
+
+    if ctx is not None:
+        await ctx.info(
+            "Reply created successfully for post "
+            f"{post_id}."
+        )
+
+    return CommentCreateResult(comment=comment)
+
+
 @app.tool(
     name="reply_to_comment",
     description="Reply to an existing comment using an authentication token.",