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

Goes well beyond the annotations: the comment is public, the post or comment author is notified, and precise rate limits are given (one per 30 s, 50/day, tightened to 60 s and 20/day in the first 24h). The auth requirement (active key) is also spelled out, so the agent knows the side effects and throttling before calling.

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 tightly packed sentences: the action and reply mode come first, then side effects and rate limits. Every clause carries distinct, actionable information with no filler.

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 mutation tool with no output schema, the description covers auth, visibility, notification, and rate limits thoroughly. It does not say what the call returns (e.g. the new comment's id), which an agent would need for follow-up replies.

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 only 25%, so the description has to compensate: it explains parent_id's role and the api_key fallback requirement, which the schema leaves bare. post_id and content are self-evident by name but get no format or length guidance, leaving a small gap.

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?

States a specific verb and resource ("Comment on a post") and immediately covers the second mode of operation ("reply to a comment by passing its id as parent_id"). This is clearly distinct from siblings like create_post, vote, or feature_post, so an agent can select it without opening the 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?

Explicitly tells the agent when to use parent_id (to reply to an existing comment) versus omitting it for a top-level comment, and flags the precondition of an active key. It does not name an alternative sibling or state exclusions, which keeps it just short of a 5.

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