Gulliver

gulliver_inspect

Read-onlyIdempotent

Explore database catalog metadata before writing SQL to choose tables and columns: list the largest tables by rows and storage, or show a table's columns and data types.

Instructions

Explore a database before writing SQL: without table, list the biggest tables first (rows, bytes, partitioning, clustering), up to limit; with table, show its columns and types. Reads catalog metadata only, so it costs nothing (the one exception is scan_rows, which runs one budget-checked sample query per table). Use this to learn sizes and partition columns; use gulliver_preflight to price a specific query, gulliver_drift to see schema changes over time.

Input Schema

Name	Required	Description
`limit`	No	Max tables to list, biggest first. Ignored when table is given.
`table`	No	Table to describe, e.g. 'events' or 'proj.ds.events' (qualify it when the name is ambiguous). Omit to list tables.
`scan_rows`	No	With sensitive: also check this many rows of text values (one budget-gated query per table; values are not returned).
`sensitive`	No	Only list columns that look like personal data or secrets, with the policy action (mask, hash, deny...).
`connection`	No	Connection name as listed by gulliver_status (from gulliver.toml or GULLIVER_DSN). Omit for the default connection.

Output Schema

Name	Required	Description	Default
`status`	Yes
`next_step`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedv0.3.1Nov 3, 2026

changedInput schema / properties / connection / description

Previous value: -"Connection name from gulliver_status. Omit for the default."New value: +"Connection name as listed by gulliver_status (from gulliver.toml or GULLIVER_DSN). Omit for the default connection."

changedInput schema / properties / limit / description

Previous value: -"Max tables to list."New value: +"Max tables to list, biggest first. Ignored when table is given."

changedInput schema / properties / table / description

Previous value: -"Table to describe, e.g. 'events' or 'proj.ds.events'. Omit to list tables."New value: +"Table to describe, e.g. 'events' or 'proj.ds.events' (qualify it when the name is ambiguous). Omit to list tables."

Changed5 schema fields changedv0.1.1Nov 3, 2026

addedInput schema / properties / scan_rows

Added value: +{
+  "default": 0,
+  "description": "With sensitive: also check this many rows of text values (one budget-gated query per table; values are not returned).",
+  "maximum": 1000,
+  "minimum": 0,
+  "title": "Scan Rows",
+  "type": "integer"
+}

addedInput schema / properties / sensitive

Added value: +{
+  "default": false,
+  "description": "Only list columns that look like personal data or secrets, with the policy action (mask, hash, deny...).",
+  "title": "Sensitive",
+  "type": "boolean"
+}

addedOutput schema / properties

Added value: +{
+  "next_step": {
+    "type": "string"
+  },
+  "status": {
+    "enum": [
+      "ok",
+      "warn",
+      "block",
+      "needs_rehearsal",
+      "needs_approval",
+      "skipped",
+      "fail",
+      "error"
+    ],
+    "type": "string"
+  }
+}

addedOutput schema / required

Added value: +[
+  "status",
+  "next_step"
+]

changedOutput schema / title

Previous value: -"gulliver_inspectDictOutput"New value: +"GulliverResult"

First observedv0.1.0Nov 1, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already cover read-only, idempotent, non-destructive safety. The description adds real context the annotations cannot: it reads catalog metadata only and costs nothing, with one disclosed exception (scan_rows runs one budget-checked sample query per table). It does not say how heavy that sample query is or what the limit budgets are, which keeps 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?

Front-loaded with the core action, then the mode split, then the cost caveat, then routing. It is dense but every clause carries information; the parenthetical about scan_rows is the one slightly awkward insert.

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 an output schema supplied, the description does not need to explain return values, and for a read-only inspection tool with full parameter docs and annotations it covers everything an agent needs to call it correctly, including the one case that incurs query cost.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3 and the schema already documents every parameter including limit, table, scan_rows, sensitive and connection. The description adds one useful interaction detail (limit is not used when table is given) and clarifies the cost profile of scan_rows, but leaves sensitive and connection entirely to the schema.

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 and resource ('Explore a database before writing SQL') and immediately splits into two concrete modes: list biggest tables without a table argument, describe columns with one. It also names the sibling tools it is not (gulliver_preflight, gulliver_drift), so an agent can place it without opening a 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 says when to use it ('learn sizes and partition columns') and names two alternatives with their distinct jobs: preflight to price a specific query, drift to see schema changes over time. The no-table vs with-table branching is spelled out as well.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server