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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds real behavioral context beyond them: completed tasks are filtered out unless includeCompleted is passed, which is non-obvious result-shaping behavior an agent would otherwise miss. It does not mention pagination behavior or result ordering.

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 tight sentences with no filler; the default-exclusion behavior is front-loaded immediately after the purpose statement so an agent reads the surprising part first.

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 read-only, four-parameter list tool with no output schema, the definition covers purpose, scoping, and the one non-obvious filtering rule. It stops short of describing what a returned task contains or whether the list is paginated beyond the limit cap, which the absence of an output schema leaves unaddressed.

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 75% — limit, mailbox, and includeCompleted are already documented in the schema, including the same default semantic the description restates. listId is undocumented in both places, and the description only gestures at it ('one To Do list'). Baseline 3 applies since the schema does most of the work.

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 concrete verb and resource with scope: 'List tasks in one To Do list.' The 'one To Do list' phrasing implicitly separates it from list_outlook_task_lists (the containers) and get_outlook_task (a single task), but no sibling is named explicitly.

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 explains the completed-task default and how to override it, which is genuine usage guidance, but it never states when this tool should be chosen over get_outlook_task or list_outlook_task_lists, nor that a valid listId must first be obtained from list_outlook_task_lists. Usage is thereby implied rather than directed.

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