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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description adds useful behavioral context by specifying that it only returns one-way trips and is deprecated. It doesn't contradict annotations and adds the one-way limitation, which goes beyond the structured fields.

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 with no waste. The deprecation warning and redirect are front-loaded, followed by a concise statement of the tool's function. Every word earns its place.

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?

The tool has an output schema (so return format is covered), annotations covering safety, and the description adds deprecation status and one-way scope. It doesn't discuss error conditions or edge cases, but for a deprecated shim tool, it provides enough context for an agent to use or avoid 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?

Schema description coverage is 100%, so the schema fully documents all three parameters. The description only implies the port relationship ('between two ports') and doesn't add detail beyond what the schema provides. Baseline 3 is appropriate when the schema carries the parameter meaning.

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 clearly states a specific verb and resource: 'Get a list of available one-way ferry trips between two ports on a specific date.' It also distinguishes itself from the sibling by explicitly naming search_trips_v2 as the preferred replacement, making its scope unambiguous.

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 description explicitly says 'Deprecated: prefer search_trips_v2' and explains what the alternative covers ('round-trip search and per-segment availability flags'). This gives clear when-to-use and when-not-to-use guidance, effectively routing the agent away from this tool.

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