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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description's job is partly done. However, the description adds unique value by explaining the error behavior ('never raises a protocol error — it returns {"error": ...}) and clarifying that it is 'FREE', which is not in annotations. It also states 'Every call is read-only and idempotent', consistent 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?

The description is well-structured with key information front-loaded (purpose, cost, scope), example usage, usage guidelines, and error handling. Each sentence adds value. Slightly redundant with annotations on idempotency/read-only, but overall efficient.

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?

Despite having an output schema, the description clarifies return values with a concrete example. It covers error behavior, fallback handling, cost, and usage context. No gaps remain for a tool with one parameter and clear sibling differentiation.

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%, so baseline is 3. The description goes beyond by providing a comprehensive example of typical input/output, listing supported language values explicitly, and explaining fallback behavior for unknown values. This adds significant meaning beyond the schema.

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 states 'Produce a focused pull-request review checklist for a language or stack', using a specific verb ('produce') and resource ('checklist'), and explicitly distinguishes itself from siblings by stating 'Not for reviewing actual code - pass code to review_diff or security_deep_dive'.

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 description explicitly says 'Use before a review, to decide what to look for' and 'Not for reviewing actual code - pass code to review_diff or security_deep_dive', clearly stating when to use it and which sibling tools to use instead. It also mentions error handling and retry behavior, providing complete usage guidance.

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