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

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

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

Schema Changelog

Changes observed during successful MCP inspections.

Changed14 schema fields changedOct 31, 2026

removedInput schema / additionalProperties
```
Removed value: -false
```
changedOutput schema / additionalProperties
```
Previous value: -trueNew value: +{}
```

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"
-        },
-        "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"
-  }
-]New value: +[
+  {
+    "items": {
+      "additionalProperties": {},
+      "properties": {
+        "columns": {
+          "type": [
+            "number",
+            "string"
+          ]
+        },
+        "details": {
+          "items": {
+            "additionalProperties": {},
+            "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": {},
+            "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": {},
+    "properties": {
+      "code": {
+        "type": "string"
+      },
+      "details": {
+        "additionalProperties": {},
+        "propertyNames": {
+          "type": "string"
+        },
+        "type": "object"
+      },
+      "error": {
+        "type": "string"
+      },
+      "internal_code": {
+        "type": "string"
+      },
+      "message": {
+        "type": "string"
+      },
+      "retry_after_s": {
+        "type": "number"
+      },
+      "retryable": {
+        "type": "boolean"
+      }
+    },
+    "required": [
+      "error"
+    ],
+    "type": "object"
+  }
+]

changedOutput schema / properties / display / additionalProperties
```
Previous value: -trueNew value: +{}
```
changedOutput schema / properties / display / properties / chart / additionalProperties
```
Previous value: -trueNew value: +{}
```
changedOutput schema / properties / display / properties / code / additionalProperties
```
Previous value: -trueNew value: +{}
```
changedOutput schema / properties / display / properties / map / additionalProperties
```
Previous value: -trueNew value: +{}
```
changedOutput schema / properties / display / properties / metric / additionalProperties
```
Previous value: -trueNew value: +{}
```
changedOutput schema / properties / insights / items / additionalProperties
```
Previous value: -trueNew value: +{}
```
changedOutput schema / properties / meta / additionalProperties
```
Previous value: -trueNew value: +{}
```
removedOutput schema / properties / meta / properties / executionTimeMs / $ref
```
Removed value: -"#/properties/data/anyOf/0/items/properties/columns"
```
addedOutput schema / properties / meta / properties / executionTimeMs / type
```
Added value: +[
+  "number",
+  "string"
+]
```

removedOutput schema / properties / meta / properties / rowCount / $ref

Removed value: -"#/properties/data/anyOf/0/items/properties/columns"

addedOutput schema / properties / meta / properties / rowCount / type
```
Added value: +[
+  "number",
+  "string"
+]
```

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 readOnly/idempotent, but the description adds material context beyond them: a 1-hour per-connection cache, the refresh bypass, the fact that it does not consume daily quota, and concrete coverage limits (MySQL indexes not yet reported, foreign keys not reported). Those caveats are exactly what prevents an agent from over-trusting the output.

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 purpose and scope, then alternative routing, then behavioral caveats. It loses a point only for the trailing sentence 'Returns tables with their columns, types, primary keys, and indexes,' which restates the opening enumeration almost verbatim and adds nothing.

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 two-parameter read tool with an output schema and full annotation coverage, everything an agent needs is present: what it returns, the structural limits, cache behavior, quota impact, and the sibling to use for value-level profiling. No ambiguity remains before invocation.

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 both parameters are already documented; the baseline would be 3. The description earns extra credit by explaining the *why* behind refresh — bypassing a 1-hour cache after a schema alteration — which the schema only states tersely as 'Force live introspection'.

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?

Specific verb ('Introspect') plus resource ('full database structure for a connection') with an enumerated scope: tables, columns, types, primary keys, indexes. It is clearly distinguished from the value-oriented siblings (analyze_table, data_profile), so an agent can tell exactly what this returns 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 Guidelines5/5

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

It states not just when to use it ('the map to build queries against an unfamiliar database') but explicitly routes away: 'Use analyze_table or data_profile instead when you need column VALUES (stats, nulls, PII) rather than structure.' It also flags when to pass refresh=true (right after altering the schema).

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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