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

readOnlyHint=true already tells the agent this is a safe read. The description adds useful content context (attendance status is included in the result), but says nothing about permissions, pagination, or result shape.

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, zero filler, with the tool's output scope front-loaded and the prerequisite second. Every clause earns its place.

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 one-param, read-only tool with no output schema, the description covers what it does, what it returns at a high level, and where the id comes from. Only the precise return shape and any authorization requirements are left unstated.

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 0%, so the description carries the burden, and it does add meaning: the single sessionId refers to a class session and should be sourced from list_gym_class_sessions. It stops short of giving the id format or any validation detail.

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 (roster of one class session) and its content scope (who is booked and whether they attended). It is clearly distinguishable from list_gym_class_sessions, which it explicitly names as a different tool.

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?

Gives a concrete prerequisite: use list_gym_class_sessions to obtain the session id. It does not, however, address when this roster is preferred over related reads such as get_gym_attendance_summary or mark_gym_class_attendance, so the exclusion guidance is incomplete.

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