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benchmarkQuery

benchmarkQuery

Read-onlyIdempotent

Measure repeatable query latency with cold runs and min/median/max warm-run timings to compare query rewrites without retrieving data.

Instructions

Measure repeatable query latency with separate cold runs and min/median/max warm-run timings. Use for comparing query rewrites, not retrieving data; timedQuery is the one-run alternative that returns rows. Bind '?'->params, ':name'->namedParams; never mix. E.g. :status -> namedParams={status:'PAID'} — key is the bare name. Returns the size of the last result (rows, columns, truncated), not the rows.

Input Schema

TableJSON Schema

Name	Required	Description
`sql`	Yes
`limit`	Yes	Row limit per run (> 0).
`params`	No	Values for '?' placeholders, in order.
`coldRuns`	No	Cold runs (default 1); executed first.
`warmRuns`	No	Warm runs (default 3).
`connection`	Yes	Database to run against. Call listConnections for valid names; do not guess.
`namedParams`	No	Values for ':name' placeholders, keyed by name.
`timeoutSeconds`	Yes	Timeout per run in seconds (> 0).

Output Schema

TableJSON Schema

Name	Required	Description
`note`	No	Additional context about support, limits, interpretation, or engine-specific behavior.
`runs`	Yes	Number of measured runs included in these timing statistics.
`allMs`	No	Individual elapsed times for all benchmark executions, in milliseconds.
`limit`	Yes	Row limit applied to the query or page size requested by the caller.
`coldMs`	No	Timing statistics for cold benchmark runs in milliseconds.
`engine`	No	Database engine that produced the result, such as PostgreSQL, Oracle, or SQL Server.
`warmMs`	No	Timing statistics for warm benchmark runs in milliseconds.
`coldRuns`	Yes	Number of cold runs executed before warm measurements.
`warmRuns`	Yes	Number of warm runs used for the primary benchmark statistics.
`resultSize`	No
`timeoutSeconds`	Yes	Per-statement timeout applied during execution, in seconds.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 15, 2026

TDQS

A4.9/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the readOnly/idempotent/destructive annotations, the description discloses key behavior: it returns only the size of the last result (rows, columns, truncated) rather than the rows themselves. It also explains the binding model ('?' vs ':name') and warns against mixing them. These are meaningful behavioral details not visible in the annotations alone.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences deliver purpose, usage guidance, binding rules, and return behavior without filler. Information is front-loaded: the core purpose appears first, then usage alternatives, then parameter and return semantics. Every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For an 8-parameter tool with an output schema, the description covers the critical invocation context: when to use it, how to bind parameters, what it returns, and why it differs from timedQuery. Remaining details like default run counts, timeout, and valid connection names are already present in the parameter schema, so nothing necessary for correct use is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already documents 88% of parameters, including descriptions for 'params' and 'namedParams', so the baseline is 3. The description adds a concrete example (':status -> namedParams={status:'PAID'}'), clarifies that the key is the bare name, and warns never to mix binding styles. This adds value but is not essential given the schema's coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('Measure') on a specific resource ('repeatable query latency') and defines the output as cold runs plus min/median/max warm-run timings. It also distinguishes itself from the sibling timedQuery by noting that timedQuery is the one-run alternative that returns rows. This makes the tool's purpose unambiguous and separable from siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly says 'Use for comparing query rewrites, not retrieving data' and names timedQuery as the alternative that returns rows. This gives the agent both a positive and negative usage condition, which is strong guidance for tool selection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.