server_metricsRetrieve non-zero ClickHouse server metrics including connections, merges, and memory usage to monitor database health.
Non-zero metrics from system.metrics (connections, merges, memory, etc.).
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive, and open-world behavior. The description adds useful behavioral context beyond that by stating that zero-valued metrics are filtered out and naming the source table, which helps an agent understand what results to expect.
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?
A single sentence that states the source, the filtering behavior, and representative categories. It is front-loaded and contains no filler or repetition of the title/annotations.
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 parameterless, read-only, idempotent tool, the description is sufficient to enable a correct call. No output schema exists, but the tool's simplicity and safe annotation profile mean the agent lacks no essential invocation guidance.
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 the baseline of 4 applies. There is no parameter ambiguity, and the description's mention of metric categories provides enough context for what can be explored.
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 identifies a specific resource (system.metrics) and a clear scope (non-zero entries covering connections, merges, memory, etc.). It implies retrieval of server-level metrics, which is enough to distinguish it from siblings like list_databases or cluster_info, though it lacks an explicit verb such as 'list' or 'get'.
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?
Usage context is implicit: an agent would select this tool when it needs server metric values rather than schema, table, or query information. However, the description does not explicitly state when to prefer this over running_queries, cluster_info, or other siblings, nor does it mention exclusion criteria.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.