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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds useful context about freshness, record counts, and fields, which goes beyond the annotations, but it does not disclose return structure or any additional behavior such as filtering or default limits.

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 one dense sentence that front-loads the purpose and lists the key metadata dimensions without repetition or filler. Every phrase 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?

For a simple, parameterless metadata tool with a read-only annotation set and an output schema present, the description is complete. It tells the agent what kind of information will be available (sources, freshness, counts, fields), which is all that is needed to select and invoke the tool 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 parameter documentation is not needed. The schema coverage is effectively 100%, and the description's mention of data sources and fields naturally frames what the returned metadata covers, which is sufficient for a parameterless call.

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 uses a specific verb ('Describes') tied to a clear resource (available vessel-registry datasets) and enumerates the content: data sources, freshness, record counts, and fields. This clearly differentiates it from the sibling tools: get_registry_stats, lookup_vessel, and search_vessel_registries.

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 intended use is implied: agents should call this when they need an overview of available datasets rather than individual vessel lookups or registry statistics. However, the description does not explicitly state when to prefer this tool over siblings or mention any exclusion criteria.

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