changed_timetable

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

No annotations are present, so the description carries the full behavioral burden. It does disclose the key filter ('only lessons that changed') and the legacy URL, but it does not mention output format, pagination, or explicitly confirm read-only behavior beyond the verb 'Get'.

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 with no filler: the first states the core purpose and the second adds the distinctive filter and legacy-URL caveat. Every sentence earns its place and the most important information is front-loaded.

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 simple read-only tool with three optional, schema-documented parameters, the description is largely sufficient: it states the scope, the filtering behavior, and a network detail. The lack of an output schema is mitigated by the resource name, though response format is not explicitly described.

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?

Input schema covers 100% of parameters with clear descriptions for 'to', 'from', and 'teacherNameFormat'. The description adds no additional parameter-level context, so it provides no value beyond the schema; baseline 3 is appropriate.

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?

Description uses a specific verb ('Get'), names the exact resource ('substitution/changed timetable'), and adds a defining behavioral detail ('Returns only lessons that changed vs original schedule'). This clearly communicates what the tool does and distinguishes it from any general timetable or lesson-list 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?

The description clearly implies the use case: retrieving substitution/changed lessons for a date range. It does not explicitly name alternatives like lessons_list for the original schedule, but it gives clear enough context for when to use this tool.

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