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

Annotations already declare idempotentHint=true and destructiveHint=false, and the description reinforces this with 'Saving again only refreshes the date.' It adds genuinely new behavior: the saved entry is a snapshot that survives deletion of the briefing, and 'chicca' only applies when the briefing has one. No auth or error behavior is disclosed, so not a 5.

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 short sentences, front-loaded with the core action, with the special-case and idempotency details following. Slightly flowery on the 'chicca' gloss, but no sentence is filler.

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 two-parameter write tool with no output schema, the description covers the mutation's persistence semantics, idempotency, and the special entry value, while annotations carry the safety profile. Only failure behavior (e.g. invalid entry_id, briefing with no chicca) is left unstated.

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 100%, so the baseline is 3, but the description adds real meaning the schema lacks: it explains what the special entry_id 'chicca' actually is (the archive story of quiet days) and conditions it on the briefing having one. briefing_id semantics are left to the schema.

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 — 'Keep one story of a briefing in the reading list (list_saved)' — and names the destination list, which implicitly separates it from save_for_later (list_read_later) and unsave_entry. The special 'chicca' entry case is also spelled out, so an agent knows exactly what this tool writes.

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 (keep a story so it persists) but there is no explicit when-to-use guidance or exclusion against the similarly named siblings save_for_later and unsave_entry. The destination list is named, which hints at the distinction, but the agent must infer it.

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