Lessons

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

Annotations already declare read-only, idempotent, non-destructive, open-world access, so the safety profile is covered. The description adds value annotations cannot: it explains what the returned lesson fields mean (ROOSTERTOETS/EXAMEN marks a test, uitgevallen=true means cancelled) and explicitly delineates what is excluded from the response. No auth or rate-limit context, but little more is needed for a read.

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?

Three tight sentences with no filler: scope first, then field semantics, then the exclusion/redirect. Every sentence carries information an agent needs.

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?

With two optional params, full schema coverage, and no output schema, the description carries the return-value burden and does so partially – it explains lesson type and cancellation but not the overall response shape (e.g. holiday field placement, ordering). Adequate for correct invocation.

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% – the date default (tomorrow), the ISO pattern, and the leerlingId requirement when multiple children are linked are all documented in the schema. The description adds no parameter-level meaning beyond what the schema already provides, so 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?

States a specific resource and scope: the timetable for exactly one Amsterdam date, plus a holiday flag. It also pre-empts confusion with the homework tool. It does not, however, distinguish itself from the sibling `schedule` tool, which an agent could plausibly pick instead.

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?

Explicitly routes the agent away from this tool for homework and test topics: "call homework for the same date." Clear usage context, but no statement of when this tool (versus `schedule`) is the right choice, and no prerequisites mentioned.

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