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

Annotations already declare idempotentHint=false, but the description goes further by naming the concrete failure mode (HTTP 409 when the student is already waitlisted) and by clarifying the side-effect boundary (no enrollment). It omits permission/auth requirements and how a supplied position interacts with existing entries, keeping it out of the top band.

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?

Two sentences, front-loaded with the WRITE marker and the core action, then the failure mode, then the endpoint. No filler sentences and nothing buried.

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-parameter create tool with full schema coverage and annotations covering safety and idempotency, the key gaps an agent faces – duplicate handling and non-enrollment semantics – are covered. Only the success response shape is unaddressed, and with no output schema that is a minor omission.

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% – class_id, student_id, notes and position are all documented in the schema, including the default for position. The description adds nothing beyond the schema for any parameter, 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?

"WRITE: put a student on a class waitlist" gives a specific verb and resource, and "Does not enroll the student" draws the boundary against the nearest mistaken action (enrollment). The sibling list has no overlapping create sibling that could confuse it, so an agent can select it unambiguously.

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?

It states the effect and the negative case ("Does not enroll"), which effectively rules out using it as an enrollment tool. It stops short of naming an alternative (e.g., an enroll tool) or stating prerequisites such as the class needing to be full, so it is clear context without explicit alternatives.

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