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

Annotations already declare destructiveHint=true and idempotentHint=true; the description adds real context beyond them by clarifying that archiving keeps rather than deletes the record and that it is terminal. The closing sentence merely restates the idempotency annotation, but the retention and irreversibility details are not derivable from structured fields.

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?

Three sentences, no filler, and the primary operation is front-loaded before the edge-case semantics of archiving. Every sentence contributes either a capability or a constraint.

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 mutation tool with nested params, no output schema, and zero schema documentation, the description covers the mutable surface and the risky path (archive). What it omits is patch semantics — whether omitted fields are left untouched — and error behavior for an invalid or already-archived taskId.

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?

With 0% schema description coverage the description must carry the load, and it does for most parameters: due_at is pinned to ISO 8601 with an offset in the user's own time zone (well beyond the bare 'date-time' format), done is explained as true=done/false=open, and archived as true-only. Gaps remain for taskId (no meaning beyond the uuid format) and title length limits.

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 and resource ('Changes a follow-up task's...') and enumerates exactly which fields are mutable: title, due_at, done, archived. An agent can distinguish this from createContactTask or listContactTasks by the operation alone, though 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?

Usage is implied rather than stated: call it to rename, reschedule, re-open/close, or archive a task. One genuinely useful precondition is given — archived tasks 'cannot be changed again' — but there is no guidance on when not to use it, no pointer to listContactTasks for obtaining a taskId, and no mention of how to reverse an archive.

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