loki_labels

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

Annotations already declare readOnlyHint=true, so the [READ] tag adds little. The description does add one genuine behavioral constraint — the hours window is capped at the tool's max lookback — and notes target defaults to config. No return-shape or volume/rate context beyond that.

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?

Purpose is front-loaded in one line, followed by a compact Args block. No filler sentences; sizing is appropriate for a two-parameter read tool.

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 simple read-only listing tool with no output schema and readOnlyHint already set, the description covers what the tool returns (distinct label names), the window semantics, and target selection. Only the max-lookback value and return format remain unstated, which is minor.

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?

Schema description coverage is 0%, so the description carries the burden and does so for both params: hours is the lookback window (with the cap caveat) and target is a config target name that can be omitted for the default. Both parameters gain meaning the bare schema lacks.

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 states a specific verb+resource: 'Distinct Loki label names present in the lookback window.' That clearly separates it from the sibling loki_label_values (which returns values for a label), even though the sibling is never named. Clear, but no explicit sibling differentiation.

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 is implied rather than stated: the agent can infer this is the tool for enumerating label names in a time window, but there is no 'when to use this vs loki_label_values or loki_query' guidance and no exclusions. Adequate minimum, with a clear gap.

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