Expose predefined queries as MCP resources

Add a resources module that registers two URIs on the server:
teslamate://queries returns a JSON index of every predefined tool with
its description and SQL source filename, and teslamate://queries/{name}
returns the raw SQL for a given query. Clients can now browse the query
catalog without invoking a tool, which is the idiomatic MCP way of
exposing read-only catalog data.

FastMCP resources cannot receive a Context, so anything that needs the
DB pool (live schema, query results) stays on the tool side.

Author: cobanov

src/teslamate_mcp/resources.py

@@ -0,0 +1,45 @@
+"""MCP resources: predefined-query metadata exposed by URI.
+
+Resource handlers in FastMCP cannot receive a Context, so anything that needs
+runtime database access (like the live schema) stays in tool form. The
+resources here are derived purely from the bundled SQL + TOML files, so they
+are safe to serve as static-content URIs.
+"""
+
+from __future__ import annotations
+
+import json
+
+from mcp.server.fastmcp import FastMCP
+
+from .tools.registry import PredefinedTool
+
+
+def register_resources(mcp: FastMCP, tools: list[PredefinedTool]) -> None:
+    """Expose the list of predefined queries and each query's raw SQL."""
+
+    by_name: dict[str, PredefinedTool] = {t.name: t for t in tools}
+
+    @mcp.resource(
+        uri="teslamate://queries",
+        name="Predefined query index",
+        description="List of every predefined query tool with its description.",
+        mime_type="application/json",
+    )
+    async def queries_index() -> str:
+        index = [
+            {"name": t.name, "description": t.description, "source": t.source} for t in tools
+        ]
+        return json.dumps(index, indent=2)
+
+    @mcp.resource(
+        uri="teslamate://queries/{name}",
+        name="Predefined query SQL",
+        description="Raw SQL source for a named predefined query.",
+        mime_type="text/sql",
+    )
+    async def query_sql(name: str) -> str:
+        try:
+            return by_name[name].sql
+        except KeyError as exc:
+            raise ValueError(f"Unknown query: {name}") from exc

src/teslamate_mcp/server.py

@@ -13,6 +13,7 @@
 
 from .config import Settings
 from .db import build_pool
+from .resources import register_resources
 from .schema import load_schema
 from .tools import (
     discover_predefined_tools,
@@ -68,6 +69,10 @@ async def lifespan(_server: FastMCP) -> AsyncIterator[AppContext]:
         statement_timeout_ms=settings.query_timeout_ms,
         row_limit=settings.custom_sql_row_limit,
     )
-    logger.info("Registered %d predefined tools + run_sql + get_database_schema", len(tools))
+    register_resources(mcp, tools)
+    logger.info(
+        "Registered %d predefined tools + run_sql + get_database_schema + 2 resources",
+        len(tools),
+    )
 
     return mcp