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

Annotations cover the safety profile (readOnlyHint, openWorldHint), but the description still adds value by disclosing data freshness ("current and upcoming") and the authoritative source (PKP PLK) plus the disruption categories returned. It does not discuss pagination, ordering, or result volume beyond the schema's limit default.

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 sentences, zero filler. Scope and content types come first, the single optional parameter and its semantics second, and the routing hint to sibling tools last.

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-optional-parameter, read-only listing tool with no output schema, the description supplies source, freshness, content categories and filter semantics — enough to call it correctly. It omits anything about result ordering or default result volume, which limits it to a 4.

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 goes beyond it by clarifying that `query` is a station-name-or-free-text match and giving worked examples ("Kraków", "ZKA") — the ZKA example is particularly useful because it signals non-station text matching.

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?

Specific verb+resource stated up front: current and upcoming railway disruptions from PKP PLK, with a concrete content inventory (track closures, ZKA replacement buses, cancellations, diversions). It also differentiates itself from siblings by noting that plan_journey, departures and trip_details already flag affected trains.

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 context is clear: reach for this when you need network-level disruption information, and the cross-reference to plan_journey/departures/trip_details tells the agent what those tools already cover. No explicit when-not or precedence rule is given, so it falls short of a 5.

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