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

The annotations already declare that this is a non-read-only, open-world, non-idempotent, destructive operation. The description adds the useful consequence that following affects the Notes feed, but it does not go further to explain reversibility, permissions, or rate limits.

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 a single efficient sentence that front-loads the action and includes the outcome. There is no redundant or wasted text.

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 simple two-parameter tool with full schema coverage and meaningful annotations, the description is nearly complete: it states the action, the target, and the effect. It could be stronger by clarifying when to choose this over subscriber-related siblings, which keeps it from a 5.

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 schema already documents the user handle/ID and the unfollow flag. The description does not add syntax or additional parameter meaning beyond what the schema provides, so the baseline of 3 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?

The description names the specific actions (follow or unfollow), the resource (a Substack user), and the effect (their Notes reach your feed). This distinguishes it from adjacent subscriber-related tools by tying it to Notes feed behavior.

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?

The description implies when to use the tool by explaining its effect on the Notes feed, but it does not explicitly compare it against alternatives such as add_subscriber or list_subscriptions. There are no stated exclusions or routing rules.

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