mcp: split mz_mcp_data_products into lightweight discovery and detailed views

doc/user/content/reference/system-catalog/mz_internal.md

@@ -542,16 +542,30 @@ each materialized view with a refresh strategy other than `on-commit`.
 
 ## `mz_mcp_data_products`
 
-The `mz_mcp_data_products` view exposes data products (indexed materialized views)
-available through the Model Context Protocol (MCP) server. Each data product
-represents a queryable dataset with a defined schema.
+The `mz_mcp_data_products` view lists data products (i.e., indexed materialized
+views) that are available through the Model Context Protocol (MCP) server and
+that the current user can access. This is a lightweight discovery view. Use
+[`mz_mcp_data_product_details`](#mz_mcp_data_product_details) for full column
+schema information.
 
 <!-- RELATION_SPEC mz_internal.mz_mcp_data_products -->
 | Field         | Type     | Meaning                                                                                  |
 | ------------- | -------- | ---------------------------------------------------------------------------------------- |
 | `object_name` | [`text`] | Fully qualified object name (database.schema.name).                                      |
 | `cluster`     | [`text`] | Cluster where the index is hosted.                                                       |
 | `description` | [`text`] | Index comment (used as data product description).                                        |
+
+## `mz_mcp_data_product_details`
+
+The `mz_mcp_data_product_details` view extends [`mz_mcp_data_products`](#mz_mcp_data_products)
+with a JSON Schema describing each data product's columns and types.
+
+<!-- RELATION_SPEC mz_internal.mz_mcp_data_product_details -->
+| Field         | Type     | Meaning                                                                                  |
+| ------------- | -------- | ---------------------------------------------------------------------------------------- |
+| `object_name` | [`text`] | Fully qualified object name (database.schema.name).                                      |
+| `cluster`     | [`text`] | Cluster where the index is hosted.                                                       |
+| `description` | [`text`] | Index comment (used as data product description).                                        |
 | `schema`      | [`jsonb`]| JSON Schema describing the object's columns and types.                                   |
 
 ## `mz_object_dependencies`

src/catalog/src/builtin.rs

@@ -11506,15 +11506,60 @@ FROM
     access: vec![PUBLIC_SELECT],
 });
 
-/// Data products exposed via MCP (Model Context Protocol) for AI agents.
+/// Lightweight data product discovery for MCP (Model Context Protocol).
 ///
-/// This view discovers indexes with comments that can be used as "data products"
-/// for AI agent access. Only indexes with SELECT privilege and cluster USAGE
-/// privilege are included.
+/// Lists indexed views with comments that the current user has privileges on.
+/// Used by the `get_data_products` and `read_data_product` MCP tools.
+/// Does not include schema details — use `mz_mcp_data_product_details` for that.
 pub static MZ_MCP_DATA_PRODUCTS: LazyLock<BuiltinView> = LazyLock::new(|| BuiltinView {
     name: "mz_mcp_data_products",
     schema: MZ_INTERNAL_SCHEMA,
     oid: oid::VIEW_MZ_MCP_DATA_PRODUCTS_OID,
+    desc: RelationDesc::builder()
+        .with_column("object_name", SqlScalarType::String.nullable(false))
+        .with_column("cluster", SqlScalarType::String.nullable(false))
+        .with_column("description", SqlScalarType::String.nullable(true))
+        .with_key(vec![0, 1, 2])
+        .finish(),
+    column_comments: BTreeMap::from_iter([
+        (
+            "object_name",
+            "Fully qualified object name (database.schema.name).",
+        ),
+        ("cluster", "Cluster where the index is hosted."),
+        (
+            "description",
+            "Index comment (used as data product description).",
+        ),
+    ]),
+    sql: r#"
+SELECT DISTINCT
+    '"' || op.database || '"."' || op.schema || '"."' || op.name || '"' AS object_name,
+    c.name AS cluster,
+    cts.comment AS description
+FROM mz_internal.mz_show_my_object_privileges op
+JOIN mz_objects o ON op.name = o.name AND op.object_type = o.type
+JOIN mz_schemas s ON s.name = op.schema AND s.id = o.schema_id
+JOIN mz_databases d ON d.name = op.database AND d.id = s.database_id
+JOIN mz_indexes i ON i.on_id = o.id
+JOIN mz_clusters c ON c.id = i.cluster_id
+JOIN mz_internal.mz_show_my_cluster_privileges cp ON cp.name = c.name
+LEFT JOIN mz_internal.mz_comments cts ON cts.id = i.id AND cts.object_sub_id IS NULL
+WHERE op.privilege_type = 'SELECT'
+  AND cp.privilege_type = 'USAGE'
+"#,
+    access: vec![PUBLIC_SELECT],
+});
+
+/// Full data product details with JSON Schema for MCP agents.
+///
+/// Extends `mz_mcp_data_products` with column types, index keys, and column
+/// comments, formatted as a JSON Schema object. Used by the
+/// `get_data_product_details` MCP tool.
+pub static MZ_MCP_DATA_PRODUCT_DETAILS: LazyLock<BuiltinView> = LazyLock::new(|| BuiltinView {
+    name: "mz_mcp_data_product_details",
+    schema: MZ_INTERNAL_SCHEMA,
+    oid: oid::VIEW_MZ_MCP_DATA_PRODUCT_DETAILS_OID,
     desc: RelationDesc::builder()
         .with_column("object_name", SqlScalarType::String.nullable(false))
         .with_column("cluster", SqlScalarType::String.nullable(false))
@@ -14482,6 +14527,7 @@ pub static BUILTINS_STATIC: LazyLock<Vec<Builtin<NameReference>>> = LazyLock::ne
         Builtin::ContinualTask(&MZ_WALLCLOCK_LAG_HISTORY_CT),
         Builtin::View(&MZ_INDEX_ADVICE),
         Builtin::View(&MZ_MCP_DATA_PRODUCTS),
+        Builtin::View(&MZ_MCP_DATA_PRODUCT_DETAILS),
     ]);
 
     builtins.extend(notice::builtins());

src/environmentd/src/http/mcp.rs

@@ -45,7 +45,11 @@ use crate::http::AuthedClient;
 use crate::http::sql::{SqlRequest, SqlResponse, SqlResult, execute_request};
 
 // To add a new tool: add entry to tools/list, add handler function, add dispatch case.
+// Discovery uses the lightweight view (no JSON schema computation).
 const DISCOVERY_QUERY: &str = "SELECT * FROM mz_internal.mz_mcp_data_products";
+// Details uses the full view with JSON schema.
+const DETAILS_QUERY_PREFIX: &str =
+    "SELECT * FROM mz_internal.mz_mcp_data_product_details WHERE object_name = ";
 
 /// MCP request errors, mapped to JSON-RPC error codes.
 #[derive(Debug, Error)]
@@ -660,10 +664,7 @@ async fn get_data_product_details(
 ) -> Result<McpResult, McpRequestError> {
     debug!(name = %name, "Executing get_data_product_details");
 
-    let query = format!(
-        "SELECT * FROM mz_internal.mz_mcp_data_products WHERE object_name = {}",
-        escaped_string_literal(name)
-    );
+    let query = format!("{}{}", DETAILS_QUERY_PREFIX, escaped_string_literal(name));
 
     let rows = execute_sql(client, &query).await?;
 

src/pgrepr-consts/src/oid.rs

@@ -788,3 +788,4 @@ pub const SOURCE_MZ_CATALOG_RAW_OID: u32 = 17067;
 pub const LOG_MZ_CLUSTER_PROMETHEUS_METRICS_OID: u32 = 17068;
 pub const FUNC_PARSE_CATALOG_ID_OID: u32 = 17069;
 pub const FUNC_PARSE_CATALOG_PRIVILEGES_OID: u32 = 17070;
+pub const VIEW_MZ_MCP_DATA_PRODUCT_DETAILS_OID: u32 = 17071;

test/sqllogictest/autogenerated/mz_internal.slt

@@ -319,6 +319,13 @@ SELECT name, type, comment FROM objects WHERE schema = 'mz_internal' AND object
 object_name  text  Fully␠qualified␠object␠name␠(database.schema.name).
 cluster  text  Cluster␠where␠the␠index␠is␠hosted.
 description  text  Index␠comment␠(used␠as␠data␠product␠description).
+
+query TTT
+SELECT name, type, comment FROM objects WHERE schema = 'mz_internal' AND object = 'mz_mcp_data_product_details' ORDER BY position
+----
+object_name  text  Fully␠qualified␠object␠name␠(database.schema.name).
+cluster  text  Cluster␠where␠the␠index␠is␠hosted.
+description  text  Index␠comment␠(used␠as␠data␠product␠description).
 schema  jsonb  JSON␠Schema␠describing␠the␠object's␠columns␠and␠types.
 
 query TTT
@@ -751,6 +758,7 @@ mz_materialization_dependencies
 mz_materialization_lag
 mz_materialized_view_refresh_strategies
 mz_materialized_view_refreshes
+mz_mcp_data_product_details
 mz_mcp_data_products
 mz_mysql_source_tables
 mz_network_policies

test/sqllogictest/information_schema_tables.slt

@@ -417,6 +417,10 @@ mz_materialized_view_refreshes
 SOURCE
 materialize
 mz_internal
+mz_mcp_data_product_details
+VIEW
+materialize
+mz_internal
 mz_mcp_data_products
 VIEW
 materialize

test/sqllogictest/mz_catalog_server_index_accounting.slt

@@ -79,7 +79,7 @@ mz_message_batch_counts_received_raw_s2_primary_idx  CREATE␠INDEX␠"mz_messag
 mz_message_batch_counts_sent_raw_s2_primary_idx  CREATE␠INDEX␠"mz_message_batch_counts_sent_raw_s2_primary_idx"␠IN␠CLUSTER␠[s2]␠ON␠"mz_introspection"."mz_message_batch_counts_sent_raw"␠("channel_id",␠"from_worker_id",␠"to_worker_id")
 mz_message_counts_received_raw_s2_primary_idx  CREATE␠INDEX␠"mz_message_counts_received_raw_s2_primary_idx"␠IN␠CLUSTER␠[s2]␠ON␠"mz_introspection"."mz_message_counts_received_raw"␠("channel_id",␠"from_worker_id",␠"to_worker_id")
 mz_message_counts_sent_raw_s2_primary_idx  CREATE␠INDEX␠"mz_message_counts_sent_raw_s2_primary_idx"␠IN␠CLUSTER␠[s2]␠ON␠"mz_introspection"."mz_message_counts_sent_raw"␠("channel_id",␠"from_worker_id",␠"to_worker_id")
-mz_notices_ind  CREATE␠INDEX␠"mz_notices_ind"␠IN␠CLUSTER␠[s2]␠ON␠[s803␠AS␠"mz_internal"."mz_notices"]␠("id")
+mz_notices_ind  CREATE␠INDEX␠"mz_notices_ind"␠IN␠CLUSTER␠[s2]␠ON␠[s804␠AS␠"mz_internal"."mz_notices"]␠("id")
 mz_object_dependencies_ind  CREATE␠INDEX␠"mz_object_dependencies_ind"␠IN␠CLUSTER␠[s2]␠ON␠[s465␠AS␠"mz_internal"."mz_object_dependencies"]␠("object_id")
 mz_object_history_ind  CREATE␠INDEX␠"mz_object_history_ind"␠IN␠CLUSTER␠[s2]␠ON␠[s534␠AS␠"mz_internal"."mz_object_history"]␠("id")
 mz_object_lifetimes_ind  CREATE␠INDEX␠"mz_object_lifetimes_ind"␠IN␠CLUSTER␠[s2]␠ON␠[s535␠AS␠"mz_internal"."mz_object_lifetimes"]␠("id")

test/sqllogictest/oid.slt

@@ -1178,3 +1178,4 @@ SELECT oid, name FROM mz_objects WHERE id LIKE 's%' AND oid < 20000 ORDER BY oid
 17068  mz_cluster_prometheus_metrics
 17069  parse_catalog_id
 17070  parse_catalog_privileges
+17071  mz_mcp_data_product_details

test/testdrive/catalog.td

@@ -644,6 +644,7 @@ mz_hydration_statuses                    ""
 mz_index_advice                          ""
 mz_materialization_dependencies          ""
 mz_materialization_lag                   ""
+mz_mcp_data_product_details              ""
 mz_mcp_data_products                     ""
 mz_notices                               ""
 mz_notices_redacted                      ""