list_schemasList all schemas in a connected PostgreSQL database to identify available namespaces before querying tables. Use it as the first step when exploring an unfamiliar database.
List every schema in the connected database. Start here when exploring an unfamiliar database, then call list_tables for the schema you care about. Returns {schemas: [name, ...]}.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.3.0Input schema / $schemaAdded value: +"http://json-schema.org/draft-07/schema#"Input schema / requiredRemoved value: -[]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, so the safe-read nature is covered. The description adds useful behavioral context by specifying 'every schema in the connected database' and providing the return shape, which is valuable since there is no output schema.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two concise sentences with no filler. The core action is front-loaded, followed by usage guidance and a compact return-format note.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a zero-parameter, read-only discoverability tool, the description is complete: it states the operation, the scope, the recommended next step, and the return shape. Nothing an agent needs to call it successfully is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool has zero parameters and an empty input schema, so there is nothing to explain. Baseline for a zero-parameter tool is 4; the description correctly omits irrelevant parameter details.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb and resource: 'List every schema in the connected database.' The scope is clear and it differentiates itself from sibling tools by framing itself as the entry point before list_tables.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly directs the agent when to use the tool: 'Start here when exploring an unfamiliar database.' It also names the next step, list_tables, giving clear usage sequencing among siblings.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.