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

Annotations already declare read-only, idempotent, non-destructive and open-world, so safety is covered. The description adds real value beyond that by describing the response shape: one-line verdicts for Snoqualmie, Stevens, White and Blewett, then 12 other passes in WSDOT's words with seasonal closures marked, then out-of-area passes, plus a check timestamp. It stops short of detailing freshness guarantees or what happens when an agency feed is unavailable.

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?

Front-loaded with the triggering condition, then the return structure in a single ordered sentence that mirrors the response layout. It is dense but every clause carries information; the phrase "Gives WithBy's verdict" is slightly clunky but not padding.

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?

With no output schema present, the description must carry the return-value burden and does so in detail: section order, sourcing attribution, closure marking, and timestamping. Combined with annotations covering the safety profile and a zero-parameter schema, an agent has everything needed to call it and interpret the result.

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?

The tool takes no parameters at all, so per the baseline this sits at 4. The description correctly spends no words on inputs and instead invests in output content, which is the right allocation for a zero-argument tool.

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 with scope: "Washington's mountain passes in depth, and the passes on the roads out of it," and explicitly frames the tool as the general/whole-list answer. The contrast with a single-pass status check is implied by "in general" and "the whole list," enough for an agent to pick between this and pass_status.

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?

The opening sentence gives concrete triggering conditions (general mountain-pass questions, which passes are open, wanting the full list) and the closing sentence excludes navigation and bookings. Strong, though it never names the sibling pass_status as the alternative for a single-pass lookup, so the routing is implied rather than stated.

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