ThinAir Data

describe_schema

Read-onlyIdempotent

Introspect the full database structure for a connection: every table, column, type, primary key, and index (MySQL connections do not report indexes yet; foreign keys are not reported) — the map to build queries against an unfamiliar database. Use analyze_table or data_profile instead when you need column VALUES (stats, nulls, PII) rather than structure. Read-only against your database. Results are cached 1 hour per connection; pass refresh=true to force a live re-introspection and bypass that cache, e.g. right after altering the schema. Does not consume daily quota. Returns tables with their columns, types, primary keys, and indexes.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`refresh`	No	Force live introspection, bypassing cache
`connection`	No	Target connection name from this tenant's inventory. Call `list_connections` to see every name + dialect, then match semantically to the user's intent (e.g. 'analytics' → a connection named `-analytics-`; 'prod' → a connection with `prod-` prefix). If the user didn't specify, use the tenant's default (first added). Do not invent names — resolve from `list_connections` output.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`data`	No
`meta`	No
`display`	No
`summary`	No
`insights`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedSep 30, 2026

changedOutput schema / properties / data / anyOf

Previous value: -[
-  {
-    "items": {
-      "additionalProperties": true,
-      "properties": {
-        "columns": {
-          "type": [
-            "number",
-            "string"
-          ]
-        },
-        "details": {
-          "items": {
-            "additionalProperties": true,
-            "properties": {
-              "defaultValue": {
-                "type": [
-                  "string",
-                  "null"
-                ]
-              },
-              "isPrimaryKey": {
-                "type": "boolean"
-              },
-              "name": {
-                "type": "string"
-              },
-              "nullable": {
-                "type": "boolean"
-              },
-              "type": {
-                "type": "string"
-              }
-            },
-            "required": [
-              "name",
-              "type"
-            ],
-            "type": "object"
-          },
-          "type": "array"
-        },
-        "name": {
-          "type": "string"
-        },
-        "primaryKeys": {
-          "items": {
-            "type": "string"
-          },
-          "type": "array"
-        }
-      },
-      "required": [
-        "name"
-      ],
-      "type": "object"
-    },
-    "type": "array"
-  },
-  {
-    "additionalProperties": true,
-    "properties": {
-      "code": {
-        "type": "string"
-      },
-      "details": {
-        "additionalProperties": {},
-        "type": "object"
-      },
-      "error": {
-        "type": "string"
-      },
-      "internal_code": {
-        "type": "string"
-      },
-      "message": {
-        "type": "string"
-      },
-      "retry_after_s": {
-        "type": "number"
-      }
-    },
-    "required": [
-      "error"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "items": {
+      "additionalProperties": true,
+      "properties": {
+        "columns": {
+          "type": [
+            "number",
+            "string"
+          ]
+        },
+        "details": {
+          "items": {
+            "additionalProperties": true,
+            "properties": {
+              "defaultValue": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "isPrimaryKey": {
+                "type": "boolean"
+              },
+              "name": {
+                "type": "string"
+              },
+              "nullable": {
+                "type": "boolean"
+              },
+              "type": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "name",
+              "type"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        "indexes": {
+          "items": {
+            "additionalProperties": true,
+            "properties": {
+              "columns": {
+                "items": {
+                  "type": "string"
+                },
+                "type": "array"
+              },
+              "isPrimary": {
+                "type": "boolean"
+              },
+              "isUnique": {
+                "type": "boolean"
+              },
+              "name": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "name",
+              "columns"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        "name": {
+          "type": "string"
+        },
+        "primaryKeys": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        }
+      },
+      "required": [
+        "name"
+      ],
+      "type": "object"
+    },
+    "type": "array"
+  },
+  {
+    "additionalProperties": true,
+    "properties": {
+      "code": {
+        "type": "string"
+      },
+      "details": {
+        "additionalProperties": {},
+        "type": "object"
+      },
+      "error": {
+        "type": "string"
+      },
+      "internal_code": {
+        "type": "string"
+      },
+      "message": {
+        "type": "string"
+      },
+      "retry_after_s": {
+        "type": "number"
+      },
+      "retryable": {
+        "type": "boolean"
+      }
+    },
+    "required": [
+      "error"
+    ],
+    "type": "object"
+  }
+]

addedOutput schema / properties / meta / properties / maskedCells
```
Added value: +{
+  "type": "number"
+}
```

addedOutput schema / properties / meta / properties / maskedColumns

Added value: +{
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / meta / properties / rowCapReached
```
Added value: +{
+  "type": "boolean"
+}
```

Changed1 schema field changedSep 15, 2026

changedOutput schema / properties / data / anyOf

Previous value: -[
-  {
-    "items": {
-      "additionalProperties": true,
-      "properties": {
-        "columns": {
-          "type": [
-            "number",
-            "string"
-          ]
-        },
-        "details": {
-          "items": {
-            "additionalProperties": true,
-            "properties": {
-              "defaultValue": {
-                "type": [
-                  "string",
-                  "null"
-                ]
-              },
-              "isPrimaryKey": {
-                "type": "boolean"
-              },
-              "name": {
-                "type": "string"
-              },
-              "nullable": {
-                "type": "boolean"
-              },
-              "type": {
-                "type": "string"
-              }
-            },
-            "required": [
-              "name",
-              "type"
-            ],
-            "type": "object"
-          },
-          "type": "array"
-        },
-        "name": {
-          "type": "string"
-        },
-        "primaryKeys": {
-          "items": {
-            "type": "string"
-          },
-          "type": "array"
-        }
-      },
-      "required": [
-        "name"
-      ],
-      "type": "object"
-    },
-    "type": "array"
-  },
-  {
-    "additionalProperties": true,
-    "properties": {
-      "code": {
-        "type": "string"
-      },
-      "details": {
-        "additionalProperties": {},
-        "type": "object"
-      },
-      "error": {
-        "type": "string"
-      },
-      "internal_code": {
-        "type": "string"
-      },
-      "message": {
-        "type": "string"
-      },
-      "retry_after_s": {
-        "type": "number"
-      }
-    },
-    "type": "object"
-  }
-]New value: +[
+  {
+    "items": {
+      "additionalProperties": true,
+      "properties": {
+        "columns": {
+          "type": [
+            "number",
+            "string"
+          ]
+        },
+        "details": {
+          "items": {
+            "additionalProperties": true,
+            "properties": {
+              "defaultValue": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "isPrimaryKey": {
+                "type": "boolean"
+              },
+              "name": {
+                "type": "string"
+              },
+              "nullable": {
+                "type": "boolean"
+              },
+              "type": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "name",
+              "type"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        "name": {
+          "type": "string"
+        },
+        "primaryKeys": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        }
+      },
+      "required": [
+        "name"
+      ],
+      "type": "object"
+    },
+    "type": "array"
+  },
+  {
+    "additionalProperties": true,
+    "properties": {
+      "code": {
+        "type": "string"
+      },
+      "details": {
+        "additionalProperties": {},
+        "type": "object"
+      },
+      "error": {
+        "type": "string"
+      },
+      "internal_code": {
+        "type": "string"
+      },
+      "message": {
+        "type": "string"
+      },
+      "retry_after_s": {
+        "type": "number"
+      }
+    },
+    "required": [
+      "error"
+    ],
+    "type": "object"
+  }
+]

Changed1 schema field changedAug 17, 2026
- addedInput schema / properties / connection / maxLength
```
Added value: +256
```

Changed2 schema fields changedMay 5, 2026

addedOutput schema / properties / display / properties / map

Added value: +{
+  "additionalProperties": true,
+  "properties": {
+    "label": {
+      "type": "string"
+    },
+    "lat": {
+      "type": "string"
+    },
+    "lon": {
+      "type": "string"
+    },
+    "title": {
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

changedOutput schema / properties / display / properties / type / anyOf

Previous value: -[
-  {
-    "enum": [
-      "table",
-      "chart",
-      "metric",
-      "code",
-      "text",
-      "list"
-    ],
-    "type": "string"
-  },
-  {
-    "type": "string"
-  }
-]New value: +[
+  {
+    "enum": [
+      "table",
+      "chart",
+      "metric",
+      "code",
+      "text",
+      "list",
+      "map"
+    ],
+    "type": "string"
+  },
+  {
+    "type": "string"
+  }
+]

Changed1 schema field changedMay 1, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": true,
+  "properties": {
+    "data": {
+      "anyOf": [
+        {
+          "items": {
+            "additionalProperties": true,
+            "properties": {
+              "columns": {
+                "type": [
+                  "number",
+                  "string"
+                ]
+              },
+              "details": {
+                "items": {
+                  "additionalProperties": true,
+                  "properties": {
+                    "defaultValue": {
+                      "type": [
+                        "string",
+                        "null"
+                      ]
+                    },
+                    "isPrimaryKey": {
+                      "type": "boolean"
+                    },
+                    "name": {
+                      "type": "string"
+                    },
+                    "nullable": {
+                      "type": "boolean"
+                    },
+                    "type": {
+                      "type": "string"
+                    }
+                  },
+                  "required": [
+                    "name",
+                    "type"
+                  ],
+                  "type": "object"
+                },
+                "type": "array"
+              },
+              "name": {
+                "type": "string"
+              },
+              "primaryKeys": {
+                "items": {
+                  "type": "string"
+                },
+                "type": "array"
+              }
+            },
+            "required": [
+              "name"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        {
+          "additionalProperties": true,
+          "properties": {
+            "code": {
+              "type": "string"
+            },
+            "details": {
+              "additionalProperties": {},
+              "type": "object"
+            },
+            "error": {
+              "type": "string"
+            },
+            "internal_code": {
+              "type": "string"
+            },
+            "message": {
+              "type": "string"
+            },
+            "retry_after_s": {
+              "type": "number"
+            }
+          },
+          "type": "object"
+        }
+      ]
+    },
+    "display": {
+      "additionalProperties": true,
+      "properties": {
+        "chart": {
+          "additionalProperties": true,
+          "properties": {
+            "chartType": {
+              "type": "string"
+            },
+            "color": {
+              "type": "string"
+            },
+            "title": {
+              "type": "string"
+            },
+            "x": {
+              "type": "string"
+            },
+            "xLabel": {
+              "type": "string"
+            },
+            "y": {
+              "anyOf": [
+                {
+                  "type": "string"
+                },
+                {
+                  "items": {
+                    "type": "string"
+                  },
+                  "type": "array"
+                }
+              ]
+            },
+            "yLabel": {
+              "type": "string"
+            }
+          },
+          "type": "object"
+        },
+        "code": {
+          "additionalProperties": true,
+          "properties": {
+            "executable": {
+              "type": "boolean"
+            },
+            "language": {
+              "anyOf": [
+                {
+                  "enum": [
+                    "sql",
+                    "json",
+                    "bash",
+                    "typescript"
+                  ],
+                  "type": "string"
+                },
+                {
+                  "type": "string"
+                }
+              ]
+            },
+            "title": {
+              "type": "string"
+            }
+          },
+          "type": "object"
+        },
+        "metric": {
+          "additionalProperties": true,
+          "properties": {
+            "label": {
+              "type": "string"
+            },
+            "status": {
+              "anyOf": [
+                {
+                  "enum": [
+                    "good",
+                    "warning",
+                    "critical"
+                  ],
+                  "type": "string"
+                },
+                {
+                  "type": "string"
+                }
+              ]
+            },
+            "trend": {
+              "anyOf": [
+                {
+                  "enum": [
+                    "up",
+                    "down",
+                    "neutral"
+                  ],
+                  "type": "string"
+                },
+                {
+                  "type": "string"
+                }
+              ]
+            },
+            "trendValue": {
+              "type": "string"
+            },
+            "unit": {
+              "type": "string"
+            },
+            "value": {
+              "type": [
+                "string",
+                "number"
+              ]
+            }
+          },
+          "type": "object"
+        },
+        "type": {
+          "anyOf": [
+            {
+              "enum": [
+                "table",
+                "chart",
+                "metric",
+                "code",
+                "text",
+                "list"
+              ],
+              "type": "string"
+            },
+            {
+              "type": "string"
+            }
+          ]
+        }
+      },
+      "type": "object"
+    },
+    "insights": {
+      "items": {
+        "additionalProperties": true,
+        "properties": {
+          "column": {
+            "type": "string"
+          },
+          "message": {
+            "type": "string"
+          },
+          "severity": {
+            "anyOf": [
+              {
+                "enum": [
+                  "info",
+                  "warning",
+                  "critical"
+                ],
+                "type": "string"
+              },
+              {
+                "type": "string"
+              }
+            ]
+          },
+          "value": {}
+        },
+        "required": [
+          "severity",
+          "message"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "meta": {
+      "additionalProperties": true,
+      "properties": {
+        "cacheHit": {
+          "type": "boolean"
+        },
+        "connection": {
+          "type": "string"
+        },
+        "dialect": {
+          "anyOf": [
+            {
+              "enum": [
+                "postgres",
+                "mysql",
+                "mssql"
+              ],
+              "type": "string"
+            },
+            {
+              "type": "string"
+            }
+          ]
+        },
+        "executionTimeMs": {
+          "$ref": "#/properties/data/anyOf/0/items/properties/columns"
+        },
+        "plan": {},
+        "rowCount": {
+          "$ref": "#/properties/data/anyOf/0/items/properties/columns"
+        },
+        "tool": {
+          "type": "string"
+        },
+        "truncated": {
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "summary": {
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

First observedApr 28, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Annotations cover the safety profile (readOnlyHint, idempotentHint, openWorldHint), and the description adds substantial context beyond them: 1-hour per-connection caching, the refresh bypass, no daily quota consumption, MySQL index-reporting limitation, and foreign keys not being reported. These are real behavioral traits an agent needs to plan around.

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?

Purpose is front-loaded in the first clause and every sentence carries information, but the final sentence ('Returns tables with their columns, types, primary keys, and indexes') restates the opening enumeration, adding slight redundancy in an already dense single paragraph.

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?

With annotations covering safety and an output schema present, the description need not explain return format in depth, and it still summarizes the shape and the known gaps (indexes on MySQL, foreign keys). Caching, quota, and alternative-tool routing complete the picture an agent needs to call it correctly.

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 meaning beyond it: refresh is framed as a cache-bypass to use after schema alteration, and connection resolution is anchored to list_connections and a default fallback. It enriches refresh semantics though the connection resolution detail largely duplicates the schema text.

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 (introspect) and resource (full database structure for a connection) and enumerates exactly what is returned: tables, columns, types, primary keys, indexes. An agent can distinguish it from analyze_table, data_profile, or query_sql without opening any schema.

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 names the alternative tools (analyze_table, data_profile) and the condition that selects them: 'when you need column VALUES (stats, nulls, PII) rather than structure.' It also states when to pass refresh=true (right after altering schema), giving concrete when-to-use guidance rather than leaving it to inference.

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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