Changes since

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

Annotations already declare read-only, non-destructive, closed-world, so the description's job is to add context — and it does: data comes from daily snapshots refreshed in the background when stale, results are grouped by course newest-first, and times are UTC. The staleness/freshness caveat is exactly the kind of thing annotations cannot convey.

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?

Front-loaded with the core action, then progressively narrower details; every clause carries information. The first sentence is long and listing-heavy, but no sentence 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?

With no output schema, the description does the work of describing returned content, field diffs, ordering, and grouping. Only the `course_id` scoping behavior is unaddressed, a minor gap for a 3-parameter read tool with annotations.

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?

At 67% schema coverage, the schema already documents `kinds` (with its value list) and `since`. The description reinforces the 26h default and UTC convention, but `course_id` is left unexplained in both the schema and the description, so it adds only modest value over structured fields.

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?

Specific verb+resource: reports what changed across a well-enumerated set of Canvas object types (pages, assignments, announcements, discussions, quizzes, events, files). It also names the data source (stored snapshots) and scope (your courses), which separates it from static-state siblings like canvas_course_snapshot.

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 best first call for a daily check" plus the 26-hour default gives the agent a clear entry-point heuristic. It doesn't name alternatives or when-not to use it (e.g., vs canvas_whats_new or a full snapshot), so it stops short of full routing guidance.

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