ThinAir Data

explain_query

Read-onlyIdempotent

Analyze a SQL query's execution plan and return plain-English performance recommendations. What runs, per dialect: postgres — EXPLAIN (FORMAT JSON), an ESTIMATED plan; the query is NOT executed and there are no measured timings (ANALYZE would execute it). mysql 8.0.18+ — EXPLAIN ANALYZE, which DOES execute the query to obtain real timings. mysql <8.0.18 — EXPLAIN FORMAT=JSON (estimated). mssql — SET SHOWPLAN_XML ON (estimated, not executed). Costs and row counts on an estimated plan are the planner's guesses: report them as estimates, not as observed behaviour. [BUILD tier]

Input Schema

Name	Required	Description	Default
`sql`	Yes	The SELECT query to analyze
`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.

Changed12 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: -[
-  {
-    "additionalProperties": true,
-    "properties": {
-      "original_sql": {
-        "type": "string"
-      },
-      "plan": {}
-    },
-    "type": "object"
-  },
-  {
-    "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: +[
+  {
+    "additionalProperties": {},
+    "properties": {
+      "original_sql": {
+        "type": "string"
+      },
+      "plan": {}
+    },
+    "type": "object"
+  },
+  {
+    "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 / rowCount / $ref
```
Removed value: -"#/properties/meta/properties/executionTimeMs"
```
addedOutput schema / properties / meta / properties / rowCount / type
```
Added value: +[
+  "number",
+  "string"
+]
```

Changed4 schema fields changedSep 30, 2026

changedOutput schema / properties / data / anyOf

Previous value: -[
-  {
-    "additionalProperties": true,
-    "properties": {
-      "original_sql": {
-        "type": "string"
-      },
-      "plan": {}
-    },
-    "type": "object"
-  },
-  {
-    "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: +[
+  {
+    "additionalProperties": true,
+    "properties": {
+      "original_sql": {
+        "type": "string"
+      },
+      "plan": {}
+    },
+    "type": "object"
+  },
+  {
+    "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: -[
-  {
-    "additionalProperties": true,
-    "properties": {
-      "original_sql": {
-        "type": "string"
-      },
-      "plan": {}
-    },
-    "type": "object"
-  },
-  {
-    "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: +[
+  {
+    "additionalProperties": true,
+    "properties": {
+      "original_sql": {
+        "type": "string"
+      },
+      "plan": {}
+    },
+    "type": "object"
+  },
+  {
+    "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"
+  }
+]

Changed2 schema fields changedAug 17, 2026
- addedInput schema / properties / connection / maxLength
```
Added value: +256
```
- addedInput schema / properties / sql / maxLength
```
Added value: +50000
```

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": [
+        {
+          "additionalProperties": true,
+          "properties": {
+            "original_sql": {
+              "type": "string"
+            },
+            "plan": {}
+          },
+          "type": "object"
+        },
+        {
+          "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": {
+          "type": [
+            "number",
+            "string"
+          ]
+        },
+        "plan": {},
+        "rowCount": {
+          "$ref": "#/properties/meta/properties/executionTimeMs"
+        },
+        "tool": {
+          "type": "string"
+        },
+        "truncated": {
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "summary": {
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

First observedApr 28, 2026

TDQS

A4/5.0

Behavior5/5

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

This is exactly the kind of disclosure annotations cannot carry: the description states that postgres/mssql/older-mysql plans are ESTIMATED and never executed, while mysql 8.0.18+ runs EXPLAIN ANALYZE and DOES execute the query for real timings. It also instructs how to report estimates vs observed behavior, which is a critical nuance for a tool annotated readOnlyHint=true.

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 purpose, then structured per dialect as a scannable list of behaviors. Every sentence carries operational weight; the trailing '[BUILD tier]' marker is internal noise that doesn't help an agent.

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

Completeness4/5

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

Given an output schema exists, there is no need to describe return values, and the description covers the risky behavior (query execution) plus dialect determinism. It doesn't mention error conditions or what happens with unsupported dialects, which is a minor omission for a tool with openWorldHint=true.

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, but the description adds real meaning by tying the `connection` parameter's dialect to materially different execution behavior. The only remaining gap is that it doesn't restate the 50k length limit or that `sql` must be a SELECT, though the schema covers both.

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

Purpose4/5

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

The first sentence gives a specific verb (analyze), resource (execution plan), and output (plain-English performance recommendations), which is far beyond a tautology. It does not explicitly distinguish itself from the sibling optimize_query, so an agent must infer the boundary between 'explain the plan' and 'optimize the query'.

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

Usage Guidelines3/5

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

Usage context is implied rather than stated: the tool is for inspecting how a SELECT runs, and the per-dialect breakdown clarifies what will happen when invoked. There is no explicit when-to-use/when-not guidance and no routing to alternatives such as optimize_query or analyze_table, so the agent has to infer selection logic.

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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