From 8fbb6178dd73ba886525aabb8efefc62ad69bb7a Mon Sep 17 00:00:00 2001
From: Alexey Samosadov <>
Date: Tue, 7 Apr 2026 17:48:03 +0300
Subject: [PATCH] fix: coerce MCP integer arguments to native Python int

ChromaDB requires native `int` for `n_results`, but the MCP JSON-RPC
transport can deliver JSON integers as floats or strings depending on
the client implementation. This causes `mempalace_search` (and any
tool with integer params like `max_hops`, `last_n`) to fail with:

  "Expected requested number of results to be a int, got 3 in query."

Fix: auto-coerce tool arguments based on the declared `input_schema`
types before calling handlers. This covers all current and future
tools generically.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 mempalace/mcp_server.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/mempalace/mcp_server.py b/mempalace/mcp_server.py
index 5902fab..fdafa71 100644
--- a/mempalace/mcp_server.py
+++ b/mempalace/mcp_server.py
@@ -725,6 +725,17 @@ def handle_request(request):
                 "id": req_id,
                 "error": {"code": -32601, "message": f"Unknown tool: {tool_name}"},
             }
+        # Coerce argument types based on input_schema.
+        # MCP JSON transport may deliver integers as floats or strings;
+        # ChromaDB and Python slicing require native int.
+        schema_props = TOOLS[tool_name]["input_schema"].get("properties", {})
+        for key, value in list(tool_args.items()):
+            prop_schema = schema_props.get(key, {})
+            declared_type = prop_schema.get("type")
+            if declared_type == "integer" and not isinstance(value, int):
+                tool_args[key] = int(value)
+            elif declared_type == "number" and not isinstance(value, (int, float)):
+                tool_args[key] = float(value)
         try:
             result = TOOLS[tool_name]["handler"](**tool_args)
             return {