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

Goes well beyond the annotations (readOnlyHint=false, openWorldHint=true, destructiveHint=false) by disclosing that no confirmation email is sent, plan limits such as access duration or caps do not apply, a new email is added to the school first, an API key is required, and each call should be confirmed with the user. This is rich, decision-relevant behavioral context.

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-loads the core purpose and stays on task, but the school-creation behavior is stated twice ('adding them to your school first if the email is new' and 'A new email is added to your school first'), which costs a little efficiency.

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 tool with no output schema, the description covers the key operational facts: free enrollment, no confirmation email, no plan limits, confirmation default, and auth requirements. Return value details are unnecessary absent an output schema, so coverage is nearly complete.

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 name, email, and course_id. The description adds marginal meaning by explaining that a new email triggers school creation, but it doesn't extend the per-parameter syntax or format beyond the schema. 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+resource+scope: enrolling a student in a course for free, and explicitly distinguishes it from paid enrollment. An agent can tell it apart from sibling read tools like teachable_list_students or teachable_send_email without opening the schema.

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?

Explains the use case clearly ('does what manual enrollment does in the Users menu', free access with no payment) and describes the enrollment-plus-school-creation flow. It sets context well but does not name explicit alternatives or when-not-to-use cases, 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.