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

Annotations already declare readOnlyHint=true, so the description adds value with the stability and size notes (small, rarely changes), which are useful behavioral traits beyond the safety flag. No contradiction.

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 sentences, each earning its place: what it returns, why to call it first, and a note on data stability/size. Front-loaded and perfectly sized without fluff.

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 simple list endpoint with an output schema, the description covers purpose, usage, and data characteristics completely. An agent has everything needed to invoke it correctly.

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 has zero parameters, so the description appropriately ignores parameter details. Baseline of 4 is correct; nothing needed to be added.

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 exactly what it returns — all WSF ferry terminals with numeric IDs, names, and abbreviations — and explicitly links it to resolving names for schedule and space tools, distinguishing it from siblings like schedules and alerts.

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 explicit direction to 'Call this first' and explains the use case (resolving human-readable names to numeric IDs needed by other tools). Also notes the list is small and rarely changes, signaling it's a stable lookup.

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