SiteCheck Trade & Energy

Dark-fleet signals from Global Fishing Watch: AIS gap

logistics_dark_fleet_ais_gap

Read-only

Dark-fleet signals from Global Fishing Watch: AIS gap events (a vessel switching its transponder off, with off/on positions, gap hours and distance) or at-sea encounters between two vessels (possible ship-to-ship transfers, with both vessels, duration and median distance), filtered by flag and vessel type over the last 1 to 30 days, newest first. Coverage is GFW's (mostly fishing, carrier, bunker and support vessels). Price: $0.002 in USDC per successful call, paid with x402 (Base, Solana or Arc); failed calls are not charged.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "logistics_dark_fleet_ais_gap"
  }
}

Input Schema

Name	Required	Description
`days`	No	Look-back window, 1 to 30 days (default 7)
`flag`	No	Vessel flag as ISO-3 code, e.g. RUS, PAN, CHN (optional)
`kind`	No	gaps (AIS off, default) or encounters (vessel meetings at sea)
`limit`	No	Events to return, 1 to 50 (default 20)
`vesselType`	No	fishing, carrier, bunker, support, cargo, tanker, passenger, other, gear (optional)

Output Schema

Name	Required	Description	Default
`to`	No
`flag`	No
`from`	No
`kind`	No
`count`	No
`total`	No
`events`	No
`source`	No
`checkedAt`	No
`vesselType`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 23, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Well beyond the readOnlyHint/openWorldHint annotations, it discloses source coverage limits (GFW, mostly fishing, carrier, bunker and support vessels), the billing model ($0.002 USDC per successful call via x402 on Base/Solana/Arc, failures free), and the ordering of results. Cost and coverage caveats are exactly the kind of behavior an agent needs before spending money or over-trusting gaps as complete.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the resource and its two event kinds, then coverage, then price — a sensible order. It is one long, heavily parenthesized sentence plus a pricing sentence, which is dense but nearly every clause carries information an agent needs.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a five-parameter, read-only, open-world data tool with full schema coverage and an output schema, the description covers purpose, both event kinds, coverage caveats, ordering and payment. Nothing essential to invoking it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds real meaning: it explains what a gap event contains (off/on positions, gap hours, distance) and what an encounter represents (ship-to-ship transfer with duration and median distance), plus the 'last 1 to 30 days, newest first' framing. It stops short of adding format hints for flag or vesselType beyond the schema's own examples.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource: it returns dark-fleet AIS gap events (transponder off, with off/on positions, gap hours, distance) or at-sea encounters (possible ship-to-ship transfers). It also names the source (Global Fishing Watch), the filter dimensions, the 1–30 day window, and the sort order (newest first), so the agent can distinguish it from generic trackers like logistics_vessel_tracker without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear context for when the tool applies (dark-fleet / AIS-gap and STS-transfer screening over the last 1–30 days) and implicitly explains the kind switch. It does not explicitly route the agent among siblings such as logistics_sanctioned_vessel_check, logistics_vessel_tracker, or logistics_maritime_piracy_alert, nor does it say when not to use it.

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

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