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

Beyond the readOnly/non-destructive annotations, it discloses that every call renders a conversation card, that it must be called at most once per answer and never used for probing, and that the card already contains ferry times and walking times so the reply should add only advice and caveats. It also documents the defaulting behavior when sections or date are omitted.

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?

Purpose is front-loaded, then usage, then alternatives, then behavioral constraints — a sensible order with no filler sentences. It is long for a description, and the 'renders a card' rule is stated twice (IMPORTANT line and 'at most ONCE'), which is slight redundancy rather than waste.

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?

An output schema exists, so return values need not be described, and the description instead covers defaults, identifier format, mandatory follow-up, and reply-style expectations. Nothing an agent needs in order to invoke this correctly is missing.

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 schema already carries per-parameter meaning and the baseline would be 3. The description still adds value by specifying that sections use the same identifiers as fetch (sat:section:…, slug or uid) in visiting order, and by explaining the fallback behavior for omitted sections and date.

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 ('Plan a multi-day trip on the Stockholm Archipelago Trail') plus concrete scope: one overnight stay or a hop across up to four stages with ferries and walking per day. It also names the sibling tools it is not (day_trip, plan_route), so an agent can distinguish it without opening any 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 explicit when-to-use triggers ('a hike over several days', 'overnight stay', 'combine two or more islands') and explicit exclusions with the correct alternatives ('Do not use for single-day trips (use day_trip) or A→B between two islands on one day (use plan_route)'). It further mandates the follow-up call to show_section_map and forbids using it to compare alternatives.

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