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

Annotations cover safety (readOnlyHint=false, idempotentHint=true, destructiveHint=false), and the description adds genuinely useful context beyond them: role gating, the free-vs-paid outcome difference, and that paid courses yield a payment link rather than an enrollment. It does not explain how 'confirm' gates the action or what the idempotency key does, so it falls short of a 5.

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 tight sentences, front-loaded with the action and scoping, then prerequisites, then the paid-course caveat. No filler, though the parenthetical preview clause is a slight interruption to the main flow.

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 4-param mutation with no output schema and only 50% schema coverage, the description covers role requirements, idempotency expectation, and the free/paid outcome, which is decent. However, it leaves the required idempotencyKey and the confirm gate undocumented, so an agent knows the 'when' better than the 'how'.

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 only 50%: courseId, idempotencyKey, and (partially) confirm lack inline descriptions, and the description does not compensate by explaining any of them. It hints at a preview/confirm mode without mapping it to the 'confirm' parameter name, leaving the required idempotencyKey entirely unexplained.

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 (enroll farm in a QuailOS Academy course) and distinguishes from siblings like get_academy_course, list_academy_courses, and list_my_academy_enrollments. The added 'preview free eligibility' mode slightly muddies a single-purpose read, but the core action is unmistakable.

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?

Provides real preconditions: requires owner, admin, or manager role, and explicitly excludes paid courses (they return a payment link and cannot be auto-enrolled via MCP). It does not name an alternative tool for the preview path, so no explicit when-instead guidance, but the constraints are concrete.

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