dbmcp_sqlite/tools/
read_query.rs

1//! MCP tool: `readQuery`.
2
3use dbmcp_pii::MaybeRedact as _;
4use dbmcp_server::pagination::Pager;
5use dbmcp_server::types::ReadQueryResponse;
6
7use dbmcp_sql::StatementKind;
8use dbmcp_sql::pagination::with_limit_offset;
9use dbmcp_sql::validation::validate_read_only;
10
11use super::prelude::*;
12use crate::types::ReadQueryRequest;
13
14const NAME: &str = "readQuery";
15const TITLE: &str = "Read Query";
16const DESCRIPTION: &str = include_str!("../../assets/tools/read_query.md");
17
18/// Marker type for the `readQuery` MCP tool.
19pub(crate) struct ReadQueryTool;
20
21impl ToolBase for ReadQueryTool {
22    type Parameter = ReadQueryRequest;
23    type Output = ReadQueryResponse;
24    type Error = ErrorData;
25
26    fn name() -> Cow<'static, str> {
27        NAME.into()
28    }
29
30    fn title() -> Option<String> {
31        Some(TITLE.into())
32    }
33
34    fn description() -> Option<Cow<'static, str>> {
35        Some(DESCRIPTION.into())
36    }
37
38    fn annotations() -> Option<ToolAnnotations> {
39        Some(
40            ToolAnnotations::new()
41                .read_only(true)
42                .destructive(false)
43                .idempotent(true)
44                .open_world(true),
45        )
46    }
47
48    fn input_schema() -> Option<Arc<JsonObject>> {
49        Some(input_schema::<Self::Parameter>(true))
50    }
51
52    fn output_schema() -> Option<Arc<JsonObject>> {
53        Some(output_schema::<Self::Output>())
54    }
55}
56
57impl AsyncTool<SqliteHandler> for ReadQueryTool {
58    async fn invoke(handler: &SqliteHandler, params: Self::Parameter) -> Result<Self::Output, Self::Error> {
59        handler.read_query(params).await
60    }
61}
62
63impl SqliteHandler {
64    /// Executes a read-only SQL query, paginating `SELECT` result rows.
65    ///
66    /// Validates that the query is read-only, then dispatches on the
67    /// classified [`StatementKind`]: `Select` is wrapped in a subquery with
68    /// a server-controlled `LIMIT`/`OFFSET`; `NonSelect` (`EXPLAIN` under
69    /// the `SQLite` dialect) is executed as-is and returned in a single
70    /// page. A malformed `cursor` is rejected by the serde deserializer
71    /// before this method is called, producing JSON-RPC `-32602`.
72    ///
73    /// # Errors
74    ///
75    /// Returns [`SqlError::ReadOnlyViolation`] if the query is not
76    /// read-only, or [`SqlError::Query`] if the backend reports an error.
77    pub async fn read_query(
78        &self,
79        ReadQueryRequest { query, cursor }: ReadQueryRequest,
80    ) -> Result<ReadQueryResponse, ErrorData> {
81        let kind = validate_read_only(&query, &sqlparser::dialect::SQLiteDialect {})?;
82
83        let (rows, next_cursor) = match kind {
84            StatementKind::Select => {
85                let pager = Pager::new(cursor, self.config.page_size);
86                let wrapped = with_limit_offset(&query, pager.limit(), pager.offset());
87                let rows = self.connection.fetch_json(wrapped.as_str(), None).await?;
88                pager.paginate(rows)
89            }
90            StatementKind::NonSelect => {
91                let rows = self.connection.fetch_json(query.as_str(), None).await?;
92                (rows, None)
93            }
94        };
95        let rows = self.redactor.redact_rows(rows).await?;
96        Ok(ReadQueryResponse { rows, next_cursor })
97    }
98}
dbmcp_sqlite/tools/read_query.rs

dbmcp_sqlite/tools/
read_query.rs
