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

Annotations already declare destructiveHint=true, idempotentHint=false and readOnlyHint=false, so the safety profile is covered structurally. The description adds useful behavioral context by framing this as an upsert, but it never says whether supplying id replaces the existing duty wholesale or merges fields — the main ambiguity for a destructive write — nor that the prompt carries the duty's instructions on each firing.

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, front-loaded with the create/update distinction, then the format detail. Zero filler, though the schedule formats could be broken out more scannably.

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 six-parameter destructive mutation with no output schema, the definition covers the schedule format and the upsert trigger but omits timezone behavior (does it default? inherit from agent?), the replace-vs-merge question, and any indication of what a successful save returns.

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 only 17%, so the description has to compensate; it does so well for schedule, enumerating three accepted formats with examples. It leaves name, timezone and prompt (beyond 'its own instructions') undefined in both schema and description, so the compensation is only partial.

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 specific verb and resource ('Adds a duty... or changes one when id is given') and defines what a duty is ('a scheduled wake-up with its own instructions'). The upsert branch is spelled out, so an agent can tell add from update without opening the schema.

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?

Gives an explicit condition for the update path (id is given) but no guidance on when to prefer this over siblings such as run_duty or get_duties, nor any prerequisites. Usage is implied by the required parameters rather than stated.

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