mysql-readonly-tool Specification

Purpose

Define a fail-closed, parameterized, read-only MySQL evidence Tool that reuses ToolBoundary and exposes only bounded ACI results.

Requirements

Requirement: SQL validation SHALL fail closed on a conservative SELECT subset

The Tool SHALL parse exactly one SQL statement with JSqlParser and SHALL accept only a single SELECT with explicit projection columns, supported predicates/grouping/ordering, INNER JOIN or LEFT JOIN, parameter placeholders and allowlisted functions. It SHALL reject writes, CTEs, subqueries, set operations, wildcard projections except COUNT(*), metadata discovery, unsupported joins/functions, FOR UPDATE, multiple statements and unknown/ambiguous AST structures.

Scenario: Reject unsupported SQL before execution

WHEN an agent submits a write statement, a second statement, a subquery, or an unallowlisted function
THEN validation fails closed and no JDBC execution is attempted

Requirement: Data-source and identifier authorization SHALL use exact independent allowlists

The Tool SHALL accept only a logical data_source ID and SHALL authorize every schema, table and column used in projection, join, predicate, grouping and ordering against the configured exact allowlist. It SHALL reject unknown data sources, schemas, tables, columns, aliases and ambiguous unqualified columns. Agent input SHALL NOT provide JDBC coordinates or authorization controls.

Scenario: Reject an identifier outside the configured allowlist

WHEN a valid-looking query references an unknown data source, table, column, alias, or ambiguous unqualified column
THEN authorization fails before connection creation and agent-provided JDBC coordinates are ignored

Requirement: Parameter binding and JDBC execution SHALL be read-only and bounded

The executor SHALL use a configured logical datasource, a read-only JDBC connection, PreparedStatement parameter binding, query timeout, max rows and Run cancellation/deadline checks. Placeholder count SHALL exactly match params. The executor SHALL not expose connection details or raw JDBC failures to the Agent.

Scenario: Execute an authorized query within read-only bounds

WHEN an authorized query has exactly matching parameters and an active Run
THEN it executes through a read-only prepared statement with timeout and row limits, while cancellation or a deadline stops execution and raw JDBC details remain hidden

Requirement: MySQL projection SHALL be bounded and evidence-aware

The projector SHALL expose only ordered columns, bounded JSON-safe rows, returned count and truncation. It SHALL enforce row, cell and total UTF-8 limits, redact sensitive column values, return NO_EVIDENCE for a successful empty result, and never expose raw JDBC metadata or credentials.

Scenario: Project bounded rows and empty evidence safely

WHEN JDBC returns rows containing oversized or sensitive values, or returns a successful empty result
THEN the projection redacts and bounds values, reports truncation when data is removed, and returns NO_EVIDENCE for the empty result without exposing metadata or credentials

Requirement: MySQL Tool SHALL reuse canonical Harness ownership

The adapter SHALL pass the exact framework tool_call_id and RunContext through the existing ToolBoundary and canonical invocation store. It SHALL not create a second ID, use a parallel store, return raw SQL results, or modify legacy audit/public runtime paths.

Scenario: Preserve framework invocation identity

WHEN the adapter invokes an authorized MySQL query
THEN ToolBoundary and the canonical invocation store receive the exact framework tool_call_id and RunContext, with no second identifier or parallel raw-result path

Requirement: The query helper script SHALL be read-only and secret-free by default

The repository query helper SHALL require connection values from environment variables, reject non-SELECT and metadata discovery SQL before connection, and SHALL NOT commit writes or expose hardcoded external connection defaults.

Scenario: Reject unsafe helper SQL without connecting

WHEN the helper receives a non-SELECT or metadata-discovery statement, or missing environment connection values
THEN it exits before opening a connection and does not reveal or invent credentials or external connection defaults

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