list_databasesList available ClickHouse databases to identify existing database names for querying and schema inspection.
List available ClickHouse databases
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v0.7.0v0.4.1v0.2.0Output schema / (root)Previous value: -nullNew value: +{
+ "description": "Generic wrapper for non-object return types.",
+ "properties": {
+ "result": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "result"
+ ],
+ "type": "object",
+ "x-fastmcp-wrap-result": true
+}v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of disclosing behavior. It merely says 'list available ClickHouse databases' without indicating that it is a read-only operation, whether it requires specific permissions, or what the return structure looks like (though an output schema exists). The description adds no behavioral context beyond the obvious intent.
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?
The description is a single, concise sentence that directly states the function with no filler or redundancy. It is appropriately sized for a simple tool with no parameters.
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?
Given the tool's simplicity, zero parameters, and presence of an output schema, the description is sufficient for an agent to understand its core function. The lack of explicit usage alternatives is a minor gap, but for a basic listing tool, the description covers the essentials.
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 the schema is empty, so there is nothing for the description to explain about parameters. According to the rubric, a baseline of 4 is appropriate when no parameters exist, and the description does not need to add anything.
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?
The description clearly states the verb 'list' and the resource 'available ClickHouse databases', making the tool's purpose unambiguous. It distinguishes itself from siblings like list_tables (tables) and run_query (queries) by explicitly targeting databases.
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?
The description gives no explicit guidance on when to use this tool versus the sibling tools. While the purpose is self-evident, there is no mention of scenarios where listing databases is preferred or when a different tool (e.g., list_tables) would be more appropriate. This leaves the agent to infer usage context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.