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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=false, and openWorldHint=true, so the 'WRITE:' label is largely redundant. The description does add genuine non-annotation context: the family is billed for this student's lessons, and the family must pre-exist. It says nothing about permissions, duplicate handling, or side effects on billing records, which matters for a destructive:true tool.

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?

One tightly-packed sentence plus the HTTP endpoint. The operation type leads, the resource follows, and the billing consequence is included without padding. Nothing is wasted.

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 15-parameter, non-idempotent, destructive create with no output schema and only 27% schema coverage, the description is thin. An agent gets the core relationship but no guidance on the many optional association fields or on how to recover from a failed/duplicated call.

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 27% across 15 parameters, so the description is expected to compensate and does not. Beyond the family association, it explains none of the optional fields (grade, school, status enum, default_service_ids, default_teacher_ids, standard_subject_ids, default_location_id), leaving many linking parameters undocumented in both places.

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 ('create a child student') plus scope ('under an existing family'), which separates it from teachworks_create_family. The parenthetical about the family being billed clarifies the resulting relationship. It stops short of explicitly contrasting with other create_* siblings, so a 4 rather than 5.

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?

The phrase 'under an existing family' communicates a real prerequisite (the family must already exist), which is useful implied usage guidance. However, there is no explicit when-to-use/when-not-to-use statement or pointer to alternatives such as teachworks_create_family or teachworks_add_student_to_lesson.

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