Explain Query

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

Annotations already declare readOnlyHint, destructiveHint, idempotentHint, openWorldHint. The description adds value by specifying the output format (JSON array of EXPLAIN QUERY PLAN rows) and explaining how it works under the hood. No contradictions.

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?

The description is efficiently structured with clear sections (main purpose, usecase, when_not_to_use, examples, what_it_returns), no wasted words, and key information front-loaded.

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?

Given the simple tool (1 param, output schema present, annotations complete), the description fully covers purpose, usage, return format, and context for selecting among siblings.

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 'query' parameter. The description's example section reinforces correct parameter usage (e.g., 'explainQuery(query="SELECT ...")'), adding context beyond the schema description.

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?

The description clearly states the tool returns execution plans to diagnose performance, with a specific verb ('explain') and resource ('SQL query'). It distinguishes from siblings like readQuery by noting it provides structured output via EXPLAIN QUERY PLAN.

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 'usecase' and 'when_not_to_use' sections explicitly state when to use (slow queries, understanding scans/indexes, index decisions) and when not (running queries via readQuery/writeQuery, checking schemas via getTableSchema), with examples.

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