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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds which aspects are diffed (engine, ruleset, input, conclusion status), which is useful but is really scope rather than behavior; it says nothing about preconditions (e.g. both versions must exist) or failure modes.

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 compact sentence with no filler, front-loading the action and the compared dimensions. It is efficient, though extremely terse for a tool with nested object inputs.

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?

An output schema exists, so return values need not be explained, but the two nested input objects are completely undocumented and there is no usage context. For a comparison tool whose correctness depends on passing the right version objects, this leaves a real gap.

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 0% and both parameters are undescribed nested objects. The word 'versions' in the description implies first/second are two reading versions, but it never states what shape they take or how they are obtained, leaving the caller to guess.

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 gives a specific verb (compares) and enumerates the comparison dimensions (engine, ruleset, input, conclusion status changes), which maps well to the title's promise of explaining why versions changed. It is clearly distinguishable from siblings like compare_conventions and compare_traditions, though it does not explicitly name them.

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?

There is no guidance on when to use this tool versus the other comparison tools (compare_conventions, compare_traditions) or the audit tools. The agent must infer the scenario from the name alone.

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