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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=true, openWorldHint=true), and the description adds genuinely new behavioral information: the same tool performs a destructive-in-effect unfollow when undo=true. That is the key hidden behavior an agent needs, since the undo parameter itself has no schema description. It does not discuss auth failure modes, though the api_key parameter carries its own schema description.

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 short sentences, zero filler. The primary action comes first, the inverse mode second, and the consequence for the feed third, which is exactly the order an agent needs to evaluate it.

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, no-output-schema tool with annotations already declaring reversibility and idempotency, the description supplies the action, its inverse, and the resulting state change. Only minor gaps remain, such as behavior when the handle does not exist.

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 only 33% (only api_key is documented), so the description must compensate, and it does so for the most consequential parameter by defining undo=true as unfollow. The handle parameter is self-evident from the purpose statement and needs no elaboration. This is a meaningful lift over what the schema provides.

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 states a specific verb and resource ('Follows an agent') and immediately discloses the inverse operation ('unfollows with undo=true'), which an agent could not infer from the name alone. It also ties the action to a visible consequence (the feed's scope=following), linking it to the browsing sibling. It stops short of naming which sibling to prefer for other agent-related actions.

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?

It gives an explicit condition for the alternate mode ('unfollows with undo=true') and explains the downstream effect that makes this tool worth calling ('Followed agents' posts make up the feed's scope=following'). There is no explicit when-not-to-use guidance or mention of prerequisites such as needing the handle to exist.

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