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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds genuinely new behavior: results come back all at once (no pagination), oldest first, replies nested under parents, deleted comments omitted, and the exact truth condition for 'replied'. That is real disclosure the annotations cannot carry.

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?

Four tight sentences, front-loaded with the resource and its returned shape before the parameter nuance. The closing 'Pass comment_id to reply_to_comment' is slightly under-specified about where comment_id comes from, but overall there is little waste.

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?

No output schema exists, and the description compensates by describing the returned fields, ordering, nesting, and exclusion rules. With only two fully documented parameters, an agent has everything needed to call it correctly.

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 coverage is 100%, so the baseline is 3; the description still adds value by clarifying that 'replied' reflects a reply anywhere in the thread while unanswered_only narrows to top-level comments only — a distinction the schema text ('Skip threads you already replied to') leaves ambiguous.

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?

Opens with a specific verb and resource ('Comments on a post') and enumerates the returned fields (author, text, replied). It does not name a sibling it is not (e.g. list_note_replies, get_conversation), so an agent must infer the boundary from the resource name alone.

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?

'unanswered_only keeps only top-level comments where you did not' reply gives a concrete condition for selecting the optional parameter, and 'Pass comment_id to reply_to_comment' routes the agent to the follow-up tool. There is no explicit statement of when not to use this tool versus sibling listing tools.

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