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

Annotations already declare this is a non-destructive write in an open-world domain, so the safety profile is handled. The description adds that slots recur weekly, but says nothing about overlap/conflict handling, permission requirements, or what happens when an identical slot already exists — relevant for a recurrence-creating 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?

A single front-loaded sentence stating what is created and the one branching semantic that matters. No filler, no repetition of the title.

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?

Seven parameters at 43% coverage and no output schema mean the description should carry more weight. It covers the key student_id branch but leaves the time/day/duration semantics and conflict behavior unaddressed, which is enough for a basic call but not for confident use.

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 only 43%, so the description needs to compensate and mostly doesn't. It explains only student_id (and its omission meaning), leaving day_of_week, start_time, duration_minutes, title, location and is_online with no extra meaning beyond the sparse schema.

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 ('Adds a recurring weekly class slot to the trainer's schedule') and clarifies the two modes: for a student, or a personal block when student_id is omitted. It never names the nearest siblings (schedule_class, update_schedule_slot, list_schedule_templates), so an agent must infer the boundary itself.

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 student-vs-personal-block distinction is implied usage guidance, but there is no explicit when-not or alternative. Nothing tells the agent whether one-off sessions belong in schedule_class instead, or how this relates to update_schedule_slot for later edits.

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