Open Waters AIS

Search vessels by name

search_vessels_by_name

Read-onlyIdempotent

Vessels whose name contains the text, case-insensitive, among every vessel the network has heard, each with its last known position. Use to turn a name into an MMSI, then get_vessels or find_vessels_near for detail. An optional bounding box narrows the search. With a feeder or partner token, text of the form IMO 9241061 finds the vessels reporting that IMO number, and a bare seven-digit number finds them ahead of the name matches.

Input Schema

TableJSON Schema

Name	Required	Description
`bbox`	No	only vessels whose last position is inside this box
`flag`	No	only vessels flying this flag: ISO 3166-1 alpha-2, e.g. NO, FI, MH
`name`	Yes	text to find in the vessel name, at least 2 characters, case-insensitive; with a feeder or partner token, IMO followed by an IMO number finds that IMO
`limit`	No	rows to return: default 50, maximum 200

Output Schema

TableJSON Schema

Name	Required	Description
`total`	Yes	vessels matched before the limit was applied
`vessels`	Yes
`truncated`	Yes	true when rows were left out: total exceeds the rows returned, so narrow the query or raise limit, or an IMO number is reported by more than the 10 vessels returned for it
`attribution`	Yes	credit line per source kind in the rows, to show with the data
`unknown_imo`	No	requested IMO numbers matching no vessel the network has heard
`unknown_mmsi`	No	requested MMSIs matching no vessel the network has heard

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 8, 2026

changedInput schema / properties / name / description

Previous value: -"text to find in the vessel name, at least 2 characters, case-insensitive"New value: +"text to find in the vessel name, at least 2 characters, case-insensitive; with a feeder or partner token, IMO followed by an IMO number finds that IMO"

changedOutput schema / properties / truncated / description

Previous value: -"true when total exceeds the rows returned; narrow the query or raise limit"New value: +"true when rows were left out: total exceeds the rows returned, so narrow the query or raise limit, or an IMO number is reported by more than the 10 vessels returned for it"

Changed1 schema field changedOct 3, 2026

changed

Output schema / properties / vessels / items / properties / sources / additionalProperties / properties / url / description

Previous value: -"the source's own page for this vessel"New value: +"the source's page for this vessel, or its public search when the source keeps no per-vessel pages"

Changed1 schema field changedOct 3, 2026

addedOutput schema / properties / vessels / items / properties / particulars / properties / callsign

Added value: +{
+  "description": "call sign as registered; the callsign in the vessel's own properties is the one AIS reports",
+  "type": "string"
+}

Changed5 schema fields changedOct 2, 2026

addedOutput schema / properties / vessels / items / properties / particulars

Added value: +{
+  "additionalProperties": false,
+  "description": "particulars as registered, merged from the enrichment sources into one vocabulary (get_vessels)",
+  "properties": {
+    "beam": {
+      "description": "beam as registered, metres",
+      "type": "number"
+    },
+    "builder": {
+      "description": "shipyard or builder",
+      "type": "string"
+    },
+    "commons_category": {
+      "description": "the category of the ship's photos on Wikimedia Commons",
+      "type": "string"
+    },
+    "deadweight": {
+      "description": "deadweight, tonnes",
+      "type": "integer"
+    },
+    "depth": {
+      "description": "registered depth, metres",
+      "type": "number"
+    },
+    "draught": {
+      "description": "design draught, metres; AIS reports the draught on the current voyage",
+      "type": "number"
+    },
+    "former_names": {
+      "description": "names the vessel has carried before, oldest first",
+      "items": {
+        "type": "string"
+      },
+      "type": [
+        "null",
+        "array"
+      ]
+    },
+    "gross_tonnage": {
+      "type": "integer"
+    },
+    "home_port": {
+      "description": "port of registry",
+      "type": "string"
+    },
+    "identification": {
+      "description": "the flag state's number for the vessel: a documented vessel's official number, else its state registration",
+      "type": "string"
+    },
+    "image": {
+      "description": "the Commons page of a photo of the ship, which shows its license and credit",
+      "type": "string"
+    },
+    "length": {
+      "description": "length as registered, metres; may differ from the AIS length",
+      "type": "number"
+    },
+    "net_tonnage": {
+      "type": "integer"
+    },
+    "operator": {
+      "type": "string"
+    },
+    "owner": {
+      "type": "string"
+    },
+    "registered_name": {
+      "description": "name as documented with the flag state, when it differs from what AIS reports",
+      "type": "string"
+    },
+    "registry": {
+      "description": "country of registry, in English",
+      "type": "string"
+    },
+    "service": {
+      "description": "flag-state service type, e.g. Towing Vessel, Passenger (Inspected), Recreational",
+      "type": "string"
+    },
+    "ship_type": {
+      "description": "kind of ship, e.g. bulk carrier, container ship, ferry",
+      "type": "string"
+    },
+    "status": {
+      "description": "flag-state status, e.g. Active, Laid Up",
+      "type": "string"
+    },
+    "tonnage_measure": {
+      "description": "how a tonnage from the flag state was measured: Convention (the international system), Regulatory (the older US system, in register tons), or Simplified (small vessels)",
+      "type": "string"
+    },
+    "wikipedia": {
+      "description": "the ship's English Wikipedia article",
+      "type": "string"
+    },
+    "yard_number": {
+      "description": "the builder's hull number",
+      "type": "string"
+    },
+    "year_built": {
+      "type": "integer"
+    }
+  },
+  "type": [
+    "null",
+    "object"
+  ]
+}

addedOutput schema / properties / vessels / items / properties / provenance

Added value: +{
+  "additionalProperties": {
+    "type": "string"
+  },
+  "description": "the source of each particulars field, by the field's name; values are keys of sources (get_vessels)",
+  "type": "object"
+}

addedOutput schema / properties / vessels / items / properties / sources

Added value: +{
+  "additionalProperties": {
+    "additionalProperties": false,
+    "properties": {
+      "credit": {
+        "description": "display credit for the source",
+        "type": "string"
+      },
+      "license": {
+        "type": "string"
+      },
+      "url": {
+        "description": "the source's own page for this vessel",
+        "type": "string"
+      }
+    },
+    "required": [
+      "credit",
+      "license"
+    ],
+    "type": "object"
+  },
+  "description": "each contributing source's credit, license, and its own page for this vessel (get_vessels)",
+  "type": "object"
+}

removedOutput schema / properties / vessels / items / properties / uscg

Removed value: -{
-  "additionalProperties": false,
-  "description": "particulars as documented with the US Coast Guard, for a US-flag vessel whose call sign and name match a vessel in its PSIX database (get_vessels)",
-  "properties": {
-    "beam": {
-      "description": "registered breadth, metres",
-      "type": "number"
-    },
-    "depth": {
-      "description": "registered depth, metres",
-      "type": "number"
-    },
-    "gross_tonnage": {
-      "type": "integer"
-    },
-    "id": {
-      "description": "the vessel's ID in PSIX",
-      "type": "integer"
-    },
-    "identification": {
-      "description": "the official number of a documented vessel, else its state registration",
-      "type": "string"
-    },
-    "length": {
-      "description": "registered length, metres",
-      "type": "number"
-    },
-    "license": {
-      "description": "public domain (U.S. government work), no credit required",
-      "type": "string"
-    },
-    "name": {
-      "description": "name as documented with the Coast Guard",
-      "type": "string"
-    },
-    "net_tonnage": {
-      "type": "integer"
-    },
-    "service": {
-      "description": "service type, e.g. Towing Vessel, Passenger (Inspected), Commercial Fishing Vessel, Recreational",
-      "type": "string"
-    },
-    "status": {
-      "description": "Coast Guard status, e.g. Active, Laid Up",
-      "type": "string"
-    },
-    "tonnage_measure": {
-      "description": "how the tonnage was measured: Convention (the international system), Regulatory (the older US system, in register tons), or Simplified (small vessels)",
-      "type": "string"
-    },
-    "year_built": {
-      "type": "integer"
-    }
-  },
-  "required": [
-    "id",
-    "license",
-    "name"
-  ],
-  "type": [
-    "null",
-    "object"
-  ]
-}

removedOutput schema / properties / vessels / items / properties / wikidata

Removed value: -{
-  "additionalProperties": false,
-  "description": "particulars as registered, from the vessel's Wikidata item found by its IMO number (get_vessels)",
-  "properties": {
-    "beam": {
-      "description": "beam as registered, metres",
-      "type": "number"
-    },
-    "builder": {
-      "description": "shipyard or builder",
-      "type": "string"
-    },
-    "commons_category": {
-      "description": "the category of the ship's photos on Wikimedia Commons",
-      "type": "string"
-    },
-    "deadweight": {
-      "description": "deadweight, tonnes",
-      "type": "integer"
-    },
-    "draught": {
-      "description": "design draught, metres; AIS reports the draught on the current voyage",
-      "type": "number"
-    },
-    "former_names": {
-      "description": "names the vessel has carried before, oldest first",
-      "items": {
-        "type": "string"
-      },
-      "type": [
-        "null",
-        "array"
-      ]
-    },
-    "gross_tonnage": {
-      "type": "integer"
-    },
-    "home_port": {
-      "description": "port of registry",
-      "type": "string"
-    },
-    "id": {
-      "description": "Wikidata item ID",
-      "type": "string"
-    },
-    "image": {
-      "description": "the Commons page of a photo of the ship, which shows its license and credit",
-      "type": "string"
-    },
-    "length": {
-      "description": "length as registered, metres; may differ from the AIS length",
-      "type": "number"
-    },
-    "license": {
-      "description": "CC0-1.0: public domain, no credit required; the photos image and commons_category lead to carry their own licenses",
-      "type": "string"
-    },
-    "operator": {
-      "type": "string"
-    },
-    "owner": {
-      "type": "string"
-    },
-    "registry": {
-      "description": "country of registry, in English",
-      "type": "string"
-    },
-    "ship_type": {
-      "description": "kind of ship, e.g. bulk carrier, container ship, oil tanker, ferry",
-      "type": "string"
-    },
-    "url": {
-      "description": "the item's page on Wikidata",
-      "type": "string"
-    },
-    "wikipedia": {
-      "description": "the ship's English Wikipedia article",
-      "type": "string"
-    },
-    "yard_number": {
-      "description": "the builder's hull number",
-      "type": "string"
-    },
-    "year_built": {
-      "description": "year the vessel entered service",
-      "type": "integer"
-    }
-  },
-  "required": [
-    "id",
-    "url",
-    "license"
-  ],
-  "type": [
-    "null",
-    "object"
-  ]
-}

Changed2 schema fields changedOct 1, 2026

addedOutput schema / properties / vessels / items / properties / uscg

Added value: +{
+  "additionalProperties": false,
+  "description": "particulars as documented with the US Coast Guard, for a US-flag vessel whose call sign and name match a vessel in its PSIX database (get_vessels)",
+  "properties": {
+    "beam": {
+      "description": "registered breadth, metres",
+      "type": "number"
+    },
+    "depth": {
+      "description": "registered depth, metres",
+      "type": "number"
+    },
+    "gross_tonnage": {
+      "type": "integer"
+    },
+    "id": {
+      "description": "the vessel's ID in PSIX",
+      "type": "integer"
+    },
+    "identification": {
+      "description": "the official number of a documented vessel, else its state registration",
+      "type": "string"
+    },
+    "length": {
+      "description": "registered length, metres",
+      "type": "number"
+    },
+    "license": {
+      "description": "public domain (U.S. government work), no credit required",
+      "type": "string"
+    },
+    "name": {
+      "description": "name as documented with the Coast Guard",
+      "type": "string"
+    },
+    "net_tonnage": {
+      "type": "integer"
+    },
+    "service": {
+      "description": "service type, e.g. Towing Vessel, Passenger (Inspected), Commercial Fishing Vessel, Recreational",
+      "type": "string"
+    },
+    "status": {
+      "description": "Coast Guard status, e.g. Active, Laid Up",
+      "type": "string"
+    },
+    "tonnage_measure": {
+      "description": "how the tonnage was measured: Convention (the international system), Regulatory (the older US system, in register tons), or Simplified (small vessels)",
+      "type": "string"
+    },
+    "year_built": {
+      "type": "integer"
+    }
+  },
+  "required": [
+    "id",
+    "license",
+    "name"
+  ],
+  "type": [
+    "null",
+    "object"
+  ]
+}

addedOutput schema / properties / vessels / items / properties / wikidata

Added value: +{
+  "additionalProperties": false,
+  "description": "particulars as registered, from the vessel's Wikidata item found by its IMO number (get_vessels)",
+  "properties": {
+    "beam": {
+      "description": "beam as registered, metres",
+      "type": "number"
+    },
+    "builder": {
+      "description": "shipyard or builder",
+      "type": "string"
+    },
+    "commons_category": {
+      "description": "the category of the ship's photos on Wikimedia Commons",
+      "type": "string"
+    },
+    "deadweight": {
+      "description": "deadweight, tonnes",
+      "type": "integer"
+    },
+    "draught": {
+      "description": "design draught, metres; AIS reports the draught on the current voyage",
+      "type": "number"
+    },
+    "former_names": {
+      "description": "names the vessel has carried before, oldest first",
+      "items": {
+        "type": "string"
+      },
+      "type": [
+        "null",
+        "array"
+      ]
+    },
+    "gross_tonnage": {
+      "type": "integer"
+    },
+    "home_port": {
+      "description": "port of registry",
+      "type": "string"
+    },
+    "id": {
+      "description": "Wikidata item ID",
+      "type": "string"
+    },
+    "image": {
+      "description": "the Commons page of a photo of the ship, which shows its license and credit",
+      "type": "string"
+    },
+    "length": {
+      "description": "length as registered, metres; may differ from the AIS length",
+      "type": "number"
+    },
+    "license": {
+      "description": "CC0-1.0: public domain, no credit required; the photos image and commons_category lead to carry their own licenses",
+      "type": "string"
+    },
+    "operator": {
+      "type": "string"
+    },
+    "owner": {
+      "type": "string"
+    },
+    "registry": {
+      "description": "country of registry, in English",
+      "type": "string"
+    },
+    "ship_type": {
+      "description": "kind of ship, e.g. bulk carrier, container ship, oil tanker, ferry",
+      "type": "string"
+    },
+    "url": {
+      "description": "the item's page on Wikidata",
+      "type": "string"
+    },
+    "wikipedia": {
+      "description": "the ship's English Wikipedia article",
+      "type": "string"
+    },
+    "yard_number": {
+      "description": "the builder's hull number",
+      "type": "string"
+    },
+    "year_built": {
+      "description": "year the vessel entered service",
+      "type": "integer"
+    }
+  },
+  "required": [
+    "id",
+    "url",
+    "license"
+  ],
+  "type": [
+    "null",
+    "object"
+  ]
+}

Changed2 schema fields changedSep 28, 2026

changedOutput schema / properties / unknown_imo / description

Previous value: -"requested IMO numbers matching no vessel heard in the last 30 minutes"New value: +"requested IMO numbers matching no vessel the network has heard"

changedOutput schema / properties / unknown_mmsi / description

Previous value: -"requested MMSIs not heard in the last 30 minutes"New value: +"requested MMSIs matching no vessel the network has heard"

Changed10 schema fields changedSep 21, 2026

addedInput schema / properties / flag

Added value: +{
+  "description": "only vessels flying this flag: ISO 3166-1 alpha-2, e.g. NO, FI, MH",
+  "type": "string"
+}

addedOutput schema / properties / unknown_imo

Added value: +{
+  "description": "requested IMO numbers matching no vessel heard in the last 30 minutes",
+  "items": {
+    "maximum": 4294967295,
+    "minimum": 0,
+    "type": "integer"
+  },
+  "type": [
+    "null",
+    "array"
+  ]
+}

addedOutput schema / properties / vessels / items / properties / beam

Added value: +{
+  "description": "beam, metres",
+  "maximum": 65535,
+  "minimum": 0,
+  "type": [
+    "null",
+    "integer"
+  ]
+}

addedOutput schema / properties / vessels / items / properties / callsign
```
Added value: +{
+  "type": "string"
+}
```

addedOutput schema / properties / vessels / items / properties / destination

Added value: +{
+  "description": "destination as typed by the crew: a port name, a UN/LOCODE, or nothing useful",
+  "type": "string"
+}

addedOutput schema / properties / vessels / items / properties / draught

Added value: +{
+  "description": "maximum static draught, metres",
+  "type": [
+    "null",
+    "number"
+  ]
+}

addedOutput schema / properties / vessels / items / properties / eta

Added value: +{
+  "description": "estimated arrival as sent, MM-DD HH:MM UTC or MM-DD; AIS carries no year, so read it as the next occurrence",
+  "type": "string"
+}

addedOutput schema / properties / vessels / items / properties / flag

Added value: +{
+  "description": "ISO 3166-1 alpha-2 code of the flag state, from the MMSI's maritime identification digits",
+  "type": "string"
+}

addedOutput schema / properties / vessels / items / properties / imo

Added value: +{
+  "description": "IMO number, once the vessel's static data has been heard",
+  "maximum": 4294967295,
+  "minimum": 0,
+  "type": "integer"
+}

addedOutput schema / properties / vessels / items / properties / length

Added value: +{
+  "description": "overall length, metres",
+  "maximum": 65535,
+  "minimum": 0,
+  "type": [
+    "null",
+    "integer"
+  ]
+}

First observedSep 18, 2026

TDQS

A4.6/5.0

Behavior4/5

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

Annotations already declare readOnlyHint/idempotentHint/openWorldHint, so the safety profile is covered; the description adds real behavioral context beyond that: results are last-known-position snapshots, coverage is network-wide rather than live, bbox restricts by last position, and token level changes matching semantics (IMO-prefix and bare-number precedence). It doesn't discuss ordering of mixed matches or pagination beyond the limit field, keeping it short of a 5.

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?

Four tight sentences, front-loaded with the definition and return shape, then usage, then the two parameter refinements. No filler or restated name/title, though the opening sentence is dense enough that 'last known position' is easy to miss on a fast read.

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?

An output schema exists, so return format needn't be explained; between the description, the fully documented schema, and the annotations, an agent has everything needed to decide to call this tool and how to shape the arguments. The token-dependent IMO behavior closes the one gap a caller could otherwise stumble into.

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 would be 3, but the description adds semantics the schema doesn't: the bbox filters on last known position specifically, and a bare seven-digit name value is matched as an IMO ahead of name matches. That precedence rule is genuinely new information an agent can't get from the schema text alone.

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?

Names a specific operation (name-substring search, case-insensitive) over a specific resource (vessels) and states scope ('among every vessel the network has heard') plus what each result carries ('its last known position'). It also distinguishes itself from siblings by pointing to get_vessels and find_vessels_near for detail.

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

Usage Guidelines5/5

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

Explicitly states the use case ('turn a name into an MMSI') and names the downstream alternatives (get_vessels, find_vessels_near) for follow-up detail. It further clarifies the narrower high-precision modes (IMO 9241061, bare seven-digit number with a feeder/partner token), so the agent knows both when to reach for this tool and when to expect exact vs. fuzzy matches.

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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