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

With no annotations, the description carries the full behavioral burden. It usefully discloses the return content (facts with source and observation date, plus facts not known yet) and implies a read-only, publication-filtered lookup via 'published facts', but says nothing about error behavior for unknown ids, rate limits, or authentication.

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?

One front-loaded sentence that states the resource first and then qualifies it; the parenthetical examples add concrete scope rather than filler. No wasted clauses.

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?

There is no output schema, so the description must describe the return value — and it does, covering the fact payload, the source/date metadata, and the 'not known yet' cases. For a simple single-id read tool this is nearly complete; only failure/error semantics are unaddressed.

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% and the schema already explains the single id parameter as 'Station id or slug from search_stations'. The description adds no further syntax or format detail, so the baseline of 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?

The description names a specific verb and resource ('All published facts for one station') and enumerates the fact categories returned (lockers, toilets, showers, step-free access), so the agent knows exactly what it retrieves. It does not name or contrast any sibling (e.g. facts_by_key or search_stations), so it falls short of a 5.

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: the singular 'one station' plus the required id signals a per-station lookup versus the sibling facts_by_key, but the description states no explicit when-to-use, when-not, or prerequisite for obtaining the id. The schema (not the description) carries the 'from search_stations' hint.

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