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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive. The description adds valuable behavioral details beyond that: it requires an API key and counts against the plan's request quota, explains pagination behavior with limit and offset, and clarifies that an empty list simply means no comments yet (not an error). This goes beyond what annotations convey.

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 concise and front-loaded with the core purpose in the first sentence. It packs essential details (pagination, quota, empty list behavior) into a few sentences without redundancy, and every sentence adds value.

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?

Given that there is no output schema and the tool is relatively simple, the description covers all necessary context: pagination, default page size, return content (authors and timestamps), empty-list interpretation, quota implications, and read-only nature. This is complete for an agent to invoke it reliably.

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?

Input schema has 100% description coverage for all three parameters, so the baseline is 3. The description reiterates the default limit of 20 and the pagination concept, but does not add semantic meaning beyond what the schema already provides. It mentions 'Page through with limit and offset' but that is usage guidance rather than parameter-specific semantics.

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 a specific verb and resource: 'Read the comment thread on one article, oldest first, paginated.' It distinguishes from sibling tools like add_reaction or get_reactions by focusing on the comment thread, and mentions the use case of reviewing reader feedback or summarising a discussion.

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?

It explicitly says 'Use it to review reader feedback or summarise a discussion' (when to use). It also states 'It reads comments only; there is no tool here for posting or moderating a reply,' which provides a clear exclusion and implies not to use it for those actions. Although it doesn't name an alternative tool, the guidance is unambiguous.

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