Explain query

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

Discloses that default mode does not execute the query, while io=true runs it with ANALYZE. Mentions safety allowlist and PG 19 specifics. No contradictions with annotations.

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?

Two succinct sentences followed by an illustrative example. Every sentence adds value, and the structure is front-loaded with purpose.

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?

With output schema present, the description covers all needed context: purpose, two modes, parameter hints, and safety. The example clarifies usage. Complete for a tool with 3 parameters.

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 has only 33% description coverage. The description compensates by explaining the io parameter effect in detail and briefly notes the database parameter, but the sql parameter is not elaborated beyond its role.

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 it returns the PostgreSQL execution plan, distinguishes default EXPLAIN from ANALYZE mode, and contrasts with execution tools like run_select. It is specific and distinguishes from 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?

Clearly explains when to use default vs io=true mode, and mentions safety allowlist. However, does not explicitly differentiate from the sibling tool analyze_query_plan, which also deals with query plans.

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