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

Annotations already establish readOnlyHint and openWorldHint, and the description adds useful behavioral detail: sailings include vessel, sailing ID, per-port local date/time, departure/arrival status, skipped ports omitted, plus pricing via x402 and no charge for failed calls. It does not describe wallet/auth requirements beyond payment method, but it is substantially informative.

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?

The description is long but front-loaded with the core purpose and dense with relevant details; pricing is placed at the end. It could be split or tightened, but every major sentence carries useful information.

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?

Given an output schema and annotations, the description is complete enough for correct invocation: it explains what the tool returns, how schedules are selected, which months are valid, and the payment model. No critical agent-facing context appears 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 schema already documents both parameters. The description restates that schedules are selected by month and route or vessel and lists schedule families, but adds little parameter-level detail beyond what the schema provides.

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 states a specific resource and action: Alaska Marine Highway System ferry schedules from official schedule grids, filtered by month and route or vessel. It is clearly distinguishable from sibling logistics tools because it names the exact ferry system and schedule families.

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 implied: retrieve schedules by month and route or vessel, and only published months are valid. However, it does not explicitly state when not to use this tool or name alternatives among the many logistics siblings.

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