explain_query

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

Annotations already establish readOnly/idempotent/non-destructive, and the description adds real behavioral value: it does not execute ANALYZE, returns a desensitized plan tree with costs, and hides condition values. That disclosure about masking and non-execution goes beyond the 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?

A single dense sentence that front-loads what the tool does and immediately appends the key non-behaviors. It is compact and wastes no words, though the semicolon-separated clauses pack several ideas that could be slightly clearer.

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 5-parameter tool with 4 required params, a deeply nested query schema, and no output schema, the description adequately frames purpose and safety but does not explain the returned plan/cost structure or parameter expectations. It is minimally viable but leaves gaps.

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 description coverage is 60%, so the schema documents connection/database/schema but leaves timeout_ms and the nested query structure without descriptions. The description adds nothing about parameter syntax or format, so it neither compensates nor regresses; 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 (生成成本摘要) and resource (结构化SELECT读取计划), and clarifies it is a read-plan cost summarizer. However it does not explicitly differentiate itself from the sibling analyze_query, relying on the phrase '不运行ANALYZE' to imply the contrast.

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?

Implies usage for server-side structured SELECT costing and signals it will not run ANALYZE, which hints at when it is preferred over analyze_query. But it gives no explicit when-to-use/when-not guidance or named alternatives among the 13 siblings.

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