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

Annotations only cover readOnlyHint=false and openWorldHint=false, and the description carries the rest exceptionally well: no price/application/date checks, prerequisite gating with the skipPrerequisiteCheck escape, passwordless account creation even on refusal, no Cubite email unless sendInvite:true, single-use magic link semantics, the fired enrollment.created webhook, and the idempotent re-enroll behavior (created:false, expiry preserved, status label reset).

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 routing, but it is a dense run-on that mixes routing, side effects, edge cases and return shape into few sentences. Every clause is substantive, yet the volume pushes past what an agent needs in one read.

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?

With no output schema and eight parameters on a mutation tool with side effects, the description enumerates the returned keys ({enrollment, user, magicLinkUrl, created, emailSent, externalReference}) and closes the loop on the constant-default course id source. Nothing material for a correct call is missing.

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% and the schema itself is unusually rich, so the baseline is 3. The description largely restates the same parameter facts (skipPrerequisiteCheck, sendInvite default, magicLinkUrl issuance) rather than adding syntax or constraints the schema lacks.

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?

Specific verb+resource ('Enroll one learner in a course by email') with an explicit account-lookup-or-create scope. It names the siblings it is not (enrollment_bulk_create for many, application_review for approvals, enrollment_update for changes), so an agent can route without opening another 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?

Explicit when-to-use and when-to-use-something-else: bulk for many learners, application_review for approving applicants, enrollment_update for changing an existing enrollment, course_list for ids. It even carves out the already-enrolled case and explains what happens instead.

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