What's new

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

The annotations already declare readOnlyHint, openWorldHint and destructiveHint, so safety is covered. The description adds real value beyond them by specifying the aggregated content categories and the lookback framing of the query. It does not discuss volume, pagination, or what happens when the window yields nothing, which is a minor omission for an aggregation 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?

Two short sentences, zero filler. The scope and activity types come first and the usage recommendation closes it out, so the agent gets the essential information immediately.

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 single-optional-parameter read tool with annotations and a fully documented schema, the definition is nearly complete: it says what is aggregated and over what default window. The absence of an output schema leaves the response shape implicit, which is the only real gap.

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 description coverage is 100% and the single parameter is fully documented in the schema, including the 26-hour default. The description confirms the temporal semantics ('since a timestamp') but adds no format or edge-case guidance beyond what the schema already states, so the 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?

The description names the resource clearly: activity across all active courses, with explicit enumeration of the five activity types (announcements, assignments, discussions, grades, messages). The 'across all active courses' scope implicitly differentiates it from per-course siblings like canvas_changes_since and canvas_list_announcements, though no sibling is named directly.

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?

'Best tool for a daily check' gives a concrete usage context, and 'since a timestamp' frames it as an incremental digest. It stops short of stating exclusions or pointing to alternatives (e.g. canvas_changes_since for a single course), so the agent must infer when not to use it.

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