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

Annotations cover read-only and open-world, and the description adds genuinely new behavior: newest-first ordering, 100 per page, inclusion of comments federated from other servers, the `replyCount` field, and a 1-credit cost. That is meaningful cost/ordering/pagination context beyond annotations. It stops short of describing cursor exhaustion or rate-limit behavior.

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 short sentences, front-loaded with what the tool returns, then scope, ordering, the sibling pointer, and cost. No filler; every clause carries information.

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?

With no output schema, the description usefully names `replyCount` and explains pagination granularity, which is enough for an agent to call and interpret results. The undocumented `cache_max_age` parameter is the one remaining 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 coverage is 67% and the schema already documents `url` (with format examples) and `cursor`. The description adds no parameter-level detail and leaves `cache_max_age` undocumented in both places, so it neither compensates for the gap nor adds value here.

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 resource ('Top-level comments on a PeerTube video') and scopes it precisely against the sibling by saying replies live in peertube.commentReplies. An agent can distinguish this from peertube_commentReplies and peertube_video without opening a 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 routes the agent to `peertube.commentReplies` for thread replies, which is the main selection ambiguity for a comments tool. It gives clear context (top-level only, newest first) but doesn't state prerequisites or when to prefer peertube_video instead.

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