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

Annotations only declare it is non-readonly, non-destructive and closed-world; the description adds real behavioral context beyond that: persistence to the user's account and an email-digest side effect. It does not detail the 409 confirmation_required flow in the prose (that lives in the confirmed param).

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?

Three short sentences, front-loaded with the core action and effects, then the precondition. Every sentence earns its place 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 7-parameter mutation tool with no output schema, the description covers the main action and confirmation gate but omits the delivery modes (enum with no description), created_via, and source_thread_id. Adequate but leaves notable gaps an agent might need when invoking.

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 57%, so the schema already carries much of the parameter meaning (label, query, targets, target_id, confirmed). The description reinforces the confirmation precondition but says nothing about delivery, created_via, or source_thread_id, so it adds only marginal value over the schema.

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+resource ('Follow a topic') and adds two concrete effects: saving to the Scout account and possibly sending email digests. It is clearly distinguishable from unfollow_topic and find_topics_to_follow, though it never names a sibling to sharpen the contrast.

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 a clear precondition: 'Call only after the user confirms the targets,' which pairs with the confirmed/targets parameters. It offers no explicit when-not or alternative-tool routing, so it stops short of the top score.

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