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

Annotations only say readOnlyHint=false and destructiveHint=false. The description adds rich behavioral detail: same-title extension (ticks kept, duplicates skipped), single-day, no repeat, saved on return with no card, and the read-back format. It also discloses that the agent cannot tick items for the athlete. No contradiction with annotations.

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?

The description is longer than minimal, but every sentence adds distinct information: purpose, use cases, extension, constraints, persistence, read-back, and boundaries. It leads with the core action and flows logically, though it could be trimmed slightly without losing value.

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 write tool with no output schema and modest annotations, the description covers what an agent needs: inputs (date, title, items), behavior (extend vs new), side effects (saved, no card), and how to verify/read back results. It also distinguishes from plan_workouts, so the agent is fully equipped to invoke it correctly.

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%, so the baseline is near 3. The description adds meaning beyond the schema for title (same title/day extends the list) and items (concrete, few words, not advice/training). It does not add color semantics, but the schema already documents color's conditional use.

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 opens with a specific verb-resource pair: 'Put a CHECKLIST on a calendar day, or ADD ITEMS to the one already there.' It also distinguishes from siblings by explicitly naming plan_workouts for training and contrasting 'not advice to read.' The single-day, no-repeat statement further separates it from recurring or copying tools.

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?

Explicit 'Use it when they want a list to work through, not advice to read' with concrete examples (race kit, evening before a test/race, travel bag). It names the alternative for training (plan_workouts), states the extension behavior, and the 'cannot tick for them' boundary, so agents know when to invoke and what to avoid.

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