discover - Isthmus

Description

Discover the full database landscape in a single call. Returns all schemas with their tables nested inside, including table type, estimated row counts, disk sizes, column counts, index presence, and comments. Call this first when connecting to a new database. One call gives the AI everything it needs to understand the database structure before diving into specific tables.

Parameters

This tool takes no parameters.

Response schema

Field	Type	Description
`schemas`	array	Array of schema overview objects (see below)

Schema overview object

Field	Type	Description
`name`	string	Schema name
`tables`	array	Tables and views in this schema (see below)

Table info object

Field	Type	Description
`schema`	string	Schema name
`name`	string	Table or view name
`type`	string	`"table"` or `"view"`
`row_estimate`	integer	Estimated row count from `pg_class`
`total_bytes`	integer	Total disk size in bytes (omitted for views)
`size_human`	string	Human-readable size, e.g. `"45 MB"` (omitted for views)
`column_count`	integer	Number of columns
`has_indexes`	boolean	Whether the table has any indexes
`comment`	string	Table comment from `COMMENT ON` or policy file (omitted if empty)

Example response

{
  "schemas": [
    {
      "name": "public",
      "tables": [
        {
          "schema": "public",
          "name": "customers",
          "type": "table",
          "row_estimate": 15420,
          "total_bytes": 2097152,
          "size_human": "2048 kB",
          "column_count": 8,
          "has_indexes": true,
          "comment": "Registered platform customers. One row per customer account."
        },
        {
          "schema": "public",
          "name": "orders",
          "type": "table",
          "row_estimate": 248000,
          "total_bytes": 47185920,
          "size_human": "45 MB",
          "column_count": 12,
          "has_indexes": true
        },
        {
          "schema": "public",
          "name": "order_summary",
          "type": "view",
          "row_estimate": 0,
          "column_count": 5,
          "has_indexes": false
        }
      ]
    },
    {
      "name": "analytics",
      "tables": [
        {
          "schema": "analytics",
          "name": "events",
          "type": "table",
          "row_estimate": 1500000,
          "total_bytes": 234881024,
          "size_human": "224 MB",
          "column_count": 6,
          "has_indexes": true
        }
      ]
    }
  ]
}

Notes

System schemas (pg_catalog, information_schema, pg_toast) are always excluded.
When the SCHEMAS environment variable is set, only the allowed schemas and their tables are returned. See Schema Filtering.
Row estimates come from pg_class.reltuples and may be stale if ANALYZE hasn’t run recently.
Comments from a policy file are merged with Postgres COMMENT ON values (Postgres comments take precedence).
This is typically the first tool an AI model calls when exploring a new database.

​Description

​Parameters

​Response schema

​Schema overview object

​Table info object

​Example response

​Notes