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

Annotations already cover read-only, idempotent, non-destructive behavior, and the description adds meaningful context beyond them: the data is historical seasonality, not live status, and each result contains a pointer to the operator's live status. It doesn't cover result cardinality or pagination, keeping it below the top score.

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 tight sentences, front-loaded with what the tool returns, followed by search guidance and the key data-freshness caveat. No 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 read-only search with a fully documented schema and no output schema, the description covers what the tool answers and its key limitation (historical, not live). It could say more about the shape of results (e.g., opening/closing dates and night-closure fields), but nothing essential for correct invocation 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 description coverage is 100%, so the baseline is 3. The description only echoes the name/country search intent and implies travel_date by mentioning 'whether it opened this year'; it adds no format or interpretation detail for lang or travel_date beyond 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 resource (European mountain pass opening/closing seasons) and a specific action (search by pass name or country), including night closures and operator live-status links. It never names or contrasts the sibling tools (find_road_trips, get_driving_rules, get_road_trip), but the domain is different enough that an agent can distinguish it without opening schemas.

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 clear usage context: search by pass name or country, and explicitly warns that seasons are records of past years, not live status, routing the agent to the operator links for current conditions. It lacks an explicit 'use X instead' statement for alternative tools, but the when-not guidance is present.

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