Explain a rule

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description still adds real behavioral context by disclosing that the tool operates on rule metadata only, not on the document, and by previewing fix-applicability as part of the answer. The remaining gap is minor since the output schema carries the return shape.

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 sentences, zero filler, and the ordering is correct: what the tool returns comes first, then the usage trigger and boundary. Every clause earns its place.

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, read-only lookup tool with both annotations and an output schema, the description supplies everything an agent needs: the input form, the trigger condition, and the fact that it is metadata-only. Nothing required for correct invocation 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 description coverage is 100% for the single rule_id parameter, so the schema already documents it. The description's example rule IDs (REF003, CIT001) mirror what the schema says and add no new syntax or format guidance. Baseline 3 applies when the schema does the heavy lifting.

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 names a specific verb and resource ('Explain a paper-preflight rule') and enumerates the exact payload the agent receives: detection logic, default severity, message template, and fix safety. It also explicitly separates itself from the sibling by stating it 'does not look at the paper,' so an agent can distinguish it from preflight_check without opening either schema.

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?

Usage is stated as an explicit trigger plus an alternative: 'Use it when a finding from `preflight_check` is unclear.' The negative boundary ('it does not look at the paper') tells the agent when this tool is the wrong choice, which is exactly the routing information needed across the preflight_* family.

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