loki_list_labels

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

No annotations exist, so the description carries the burden. It implies a read-only listing operation and discloses performance behavior ('Shorter is faster'), but it does not mention potential result size, auth needs, or any side effects. This is adequate but not rich.

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 sentences: the first states the tool's purpose, the second explains the parameter. No filler, front-loaded information, and every sentence earns its place.

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 single-parameter listing tool with an output schema present, the description covers the essential behavior and parameter semantics. The sibling distinction is clear from the purpose statement, and no missing prerequisites or caveats are critical.

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 input schema only defines 'lookback' as a string with a default, giving no semantic detail. The description compensates fully by specifying valid examples ('1h', '24h', '7d'), the default, and the performance tradeoff. This adds significant meaning beyond the schema.

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 opens with 'List all label names Loki has seen', which is a specific verb+resource statement. It clearly distinguishes this from the sibling tool loki_list_label_values, which lists values for a given label. The purpose is unambiguous.

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 provides clear context by stating the lookback window and the default ('Default 1h'), plus a practical performance hint ('Shorter is faster'). It does not explicitly mention alternatives or when not to use, but the usage context is clear enough for straightforward selection.

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