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

readOnlyHint=true already tells the agent this is a safe read. The description adds scope ('free seats'), but that framing is somewhat at odds with the only_booked/only_not_booked filters, which suggest departures without free seats can also be returned. It says nothing about pagination behavior despite limit/offset existing.

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 short sentences, front-loaded with the resource and scope; nothing is wasted. The API endpoint is marginally redundant for an agent but reinforces the underlying contract, so only a small deduction.

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 an 11-parameter read tool with no output schema, the description never indicates what an availability record contains (departure time, seats, booking state), which would help the agent interpret results. Annotations cover the safety profile and the schema covers inputs, so this is the main remaining gap but it is a real one.

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 description coverage is 100%, so all 11 parameters (date bounds, seats minimum, language, booking filters, paging) are already documented in the schema. The description adds no syntax, defaults, or interaction rules (e.g., that only_booked and only_not_booked are mutually exclusive), so the baseline 3 applies.

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 ('list departures ... for one activity') and grounds it in a concrete API endpoint, so the agent knows exactly what is being fetched. It does not name or differentiate itself from the sibling trekksoft_list_availabilities (the cross-activity variant), leaving that distinction to inference from 'one activity'.

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 only implied: 'for one activity' suggests this is the single-activity counterpart to the broader list tool, and the required activity_id makes the prerequisite obvious. There is no explicit when-to-use / when-not guidance and no mention of trekksoft_list_availabilities as the alternative when no activity is chosen.

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