Estimate bytes scanned and projected USD cost for a read-only SQL query without executing it.
Estimate bytes scanned and projected cost in USD for a read-only SQL query without executing it.
| Name | Required | Description | Default |
|---|---|---|---|
| sql | Yes | Read-only SQL query to dry-run |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full disclosure burden. It does convey the most important trait — the query is not executed and only estimated bytes/cost are returned — but says nothing about permissions required, behavior on non-read-only or malformed SQL, or whether estimates are exact or approximate.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
One front-loaded sentence that names the output (bytes scanned, USD cost) and the safety constraint (no execution) with zero filler. Nothing redundant or vague.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a one-parameter, no-output-schema tool, the description covers purpose, output content, and the non-execution guarantee. Only minor gaps remain: no error/limitation behavior and no explicit routing to execute_readonly_query, but nothing essential to invoking it is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% for the single 'sql' parameter, so the schema already documents the argument and its read-only dry-run semantics. The description adds no syntax, dialect, or format detail beyond what the schema provides, so the baseline 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb (estimate), the resource (bytes scanned and projected USD cost for a SQL query), and the key scope qualifier (read-only, without executing). This clearly separates it from sibling execute_readonly_query and from the listing/describe siblings.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The phrase 'without executing it' implies the natural use case: dry-run before running execute_readonly_query. It gives clear context for when the tool applies but stops short of an explicit 'use this before executing' rule or any stated exclusions (e.g., only for supported query types).
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.