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

Annotations already declare readOnly and openWorld, and the description adds substantial behavioral context: GFW coverage limits, newest-first ordering, per-call pricing, payment networks, and that failed calls are not charged. Nothing contradicts the annotations.

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 dense but front-loaded: it leads with what the tool returns, then filters and ordering, then coverage and billing. Every sentence carries useful selection or invocation 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 the output schema and full parameter documentation, the description supplies the remaining operational context an agent needs: event types, coverage limitations, ordering, and billing behavior.

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 every parameter. The description reinforces meanings such as gaps versus encounters and the look-back window, but does not add significant syntax or format detail beyond the schema.

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 behavior: Global Fishing Watch dark-fleet signals covering AIS gap events or at-sea encounters, with the key fields and filters named. It clearly distinguishes the two event kinds an agent can request.

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?

It makes the usage context clear: filter by flag and vessel type over a 1-30 day window, newest first, and choose gaps versus encounters. It does not explicitly say when not to use it or name sibling alternatives such as logistics_vessel_tracker or logistics_sanctioned_vessel_check.

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