diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
index f3845a37..56b98924 100644
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -810,7 +810,7 @@ For each language recon cleared, do the AST work and produce a `RepoInventory`:
   `#[...]` is parsed as a `comment` node — so the attribute is read from the
   comment text immediately preceding the method via regex. Emits
   `ToolDef{Kind: mcp_tool, Language: php}`, so deriveSDKsDetected stamps SDKMCP
-  and the mcp/ pack's `language: php` rules (MCP-019/020) audit them. Multi-line
+  and the mcp/ pack's `language: php` rules (MCP-019/020/029) audit them. Multi-line
   `#[...]` attributes, `#[McpResource]` / `#[McpPrompt]`, and PHP body-fact
   predicates are v1 gaps.
 - **DiscoverRustMCPTools** (`rust_mcp.go`) — Rust MCP tools parsed with
diff --git a/internal/rules/policies_test.go b/internal/rules/policies_test.go
index 65af6c0a..f2a58523 100644
--- a/internal/rules/policies_test.go
+++ b/internal/rules/policies_test.go
@@ -1361,6 +1361,21 @@ def run_cmd(name: str) -> str:
 		kind: models.KindMCPTool, lang: models.LanguagePHP, wantFires: false,
 		src: "<?php\nuse PhpMcp\\Server\\Attributes\\McpTool;\nclass T {\n    #[McpTool(name: 'summarize_invoice', description: 'Summarize')]\n    public function summarizeInvoice(string $input): string { return $input; }\n}\n",
 	},
+	{
+		name: "MCP-029 fires on PHP untyped params", ruleID: "MCP-029",
+		kind: models.KindMCPTool, lang: models.LanguagePHP, wantFires: true,
+		src: "<?php\nuse PhpMcp\\Server\\Attributes\\McpTool;\nclass T {\n    #[McpTool(name: 'search_docs', description: 'Search')]\n    public function searchDocs($query, $limit) { return $query; }\n}\n",
+	},
+	{
+		name: "MCP-029 silent with PHP type hints", ruleID: "MCP-029",
+		kind: models.KindMCPTool, lang: models.LanguagePHP, wantFires: false,
+		src: "<?php\nuse PhpMcp\\Server\\Attributes\\McpTool;\nclass T {\n    #[McpTool(name: 'search_docs', description: 'Search')]\n    public function searchDocs(string $query, int $limit): string { return $query; }\n}\n",
+	},
+	{
+		name: "MCP-029 silent on zero-param PHP tool", ruleID: "MCP-029",
+		kind: models.KindMCPTool, lang: models.LanguagePHP, wantFires: false,
+		src: "<?php\nuse PhpMcp\\Server\\Attributes\\McpTool;\nclass T {\n    #[McpTool(name: 'ping', description: 'Health check')]\n    public function ping(): string { return 'ok'; }\n}\n",
+	},
 	{
 		name: "MCP-021 fires on Rust tool with no description", ruleID: "MCP-021",
 		kind: models.KindMCPTool, lang: models.LanguageRust, wantFires: true,
diff --git a/testdata/rules-fixture/mcp/tool_definition.yaml b/testdata/rules-fixture/mcp/tool_definition.yaml
index 1e843121..fdc49545 100644
--- a/testdata/rules-fixture/mcp/tool_definition.yaml
+++ b/testdata/rules-fixture/mcp/tool_definition.yaml
@@ -309,3 +309,27 @@ rules:
     fix: >
       Rename the method (or set the `#[tool]` `name = "..."` argument) to a
       verb-object form, e.g. `summarize_invoice`, `fetch_weather`.
+
+  - id: MCP-029
+    title: PHP MCP tool has no type-annotated parameters
+    severity: medium
+    confidence: 0.85
+    language: php
+    applies_to:
+      - mcp_tool
+    scope: tool
+    match:
+      has_params: true
+      has_typed_params: false
+    explanation: >
+      MCP derives a PHP tool's advertised input JSON schema from the handler's
+      parameter type hints. PHP type hints are optional; without them the
+      published schema is unconstrained, so connecting models send unvalidated
+      inputs that frequently cause runtime errors inside the server. Go, C#,
+      and Rust MCP tools cannot express this gap — those languages are
+      statically typed — which is why this sibling of MCP-002 exists only for
+      PHP.
+    fix: >
+      Add type hints to every parameter (`function search(string $query, int
+      $limit = 10): array`). Use typed properties or DTO classes for structured
+      inputs so the published schema constrains them.