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

Annotations declare destructiveHint=true and readOnlyHint=false, and the description adds context the annotations cannot: mutations are in place and preserve learner progress, omitted fields stay unchanged, a non-enrolled learner yields a not-found error, and no email is sent. It also discloses the return payload shape, which is significant given there is no output schema.

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 purpose, then alternatives, then semantics, with no filler sentences. It is dense and long for a single tool, but each clause (waitlist mechanics, no-email behavior, return shape) carries information an agent needs, so the length is largely earned.

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?

No output schema exists, so the description compensates by listing the returned enrollment fields (courseId, userId, status, isWaitListed, enrolledAt, expiresAt, user). Combined with annotation-covered safety and explicit error behavior, nothing needed to invoke this mutation correctly 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 coverage is 100%, so the baseline is 3, but the description adds real value beyond the schema: it explains that identity is email or userId, that omitted fields are unchanged, and the non-obvious interaction of isWaitListed:false with status:"completed" to surface Start/Continue. It stops short of documenting any edge semantics the schema already owns.

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 ('Change one existing enrollment in place') and enumerates the three mutable aspects: access expiry, waitlist membership, and status label. It directly distinguishes itself from enrollment_create and enrollment_revoke by naming both siblings, so an agent can select it without opening any 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 routing: 'Use it for every change to an enrollment that exists; to add one use enrollment_create, to remove one enrollment_revoke.' It also names the waitlist-promotion idiom (isWaitListed:false with status:"completed") and the prerequisite that the learner must be enrolled, covering when-not (not-found error) and alternatives.

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