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

Annotations cover the safety profile (readOnly=false, destructive=false, openWorld=true), and the description adds meaningful context beyond them: it discloses the confirmation default and how to disable it, the 'one class at a time' sending constraint, that it reaches other people, and the required API key/app access. This is rich behavioral disclosure.

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?

Front-loaded with the core action and overall efficient, but it carries some redundancy ('reaches the members registered' and 'reaches the members currently registered'; the confirmation point appears twice). Not wasteful enough to drop below 4.

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 mutation/messaging tool with no output schema and openWorldHint, the description covers side effects, confirmation policy, per-call constraint, and auth needs. It is complete enough to call correctly, though it does not describe delivery results or failure handling.

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%, so the schema already documents body, channel, subject, and class_id. The description's 'by email, text or both' merely restates the channel enum and adds no syntax or format detail beyond the schema, so the baseline 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?

States a specific verb and resource ('Email or text the members registered in a class') with clear scope ('currently registered'). It is distinguishable from read-oriented siblings like pushpress_get_class_roster because it clearly performs a send action.

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?

Gives clear usage context (reaches currently registered members via email/text/both) and explicit confirmation guidance ('By default you confirm each call; you can switch that off for this tool. Reaches other people: confirm with the user before each call'). It does not name a specific alternative tool to prefer, so it stops short of a 5.

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