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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=false, and openWorldHint=true, so the safety profile is carried by structured data. The description adds the actual behavioral effect — you are subscribed to new-comment notifications — which annotations cannot express, but it says nothing about reversibility, permission requirements, or whether stopping removes historical notification state. Note destructiveHint=true is consistent with 'stop' removing a follow, not a contradiction.

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?

A single ten-word sentence with the effect front-loaded and zero filler. It is efficient, though the trailing 'or stop' is clipped enough to require a second read.

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 three-parameter toggle with full schema documentation, existing annotations, and no output schema, the description is adequate but thin — an agent gets the gist but must infer the follow/unfollow toggle model and any membership prerequisites from the schema and annotations alone.

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%: group format, the post_id sourcing from list_posts, and the following=false semantics and default are all documented in the schema. The description adds no meaning beyond that, so the baseline 3 for high coverage applies.

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 concrete effect (notifications for new comments on a post) and its inverse ('or stop'), plus the resource 'post', which is enough to distinguish it from like_post, comment_on_post, and get_post. It never uses the verb 'follow' explicitly and leaves the toggle framing (follow vs. unfollow in one tool) to the reader, so it stops short of a precise 5.

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?

'or stop' implies the two usage modes (start receiving notifications, stop receiving them), but there is no explicit when-to-use guidance, no prerequisites (e.g., must be a group member, must have post_id from list_posts — that hint lives only in the schema), and no named alternative when a different tool would be better.

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