list_prometheus_label_values

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions filtering and time range capabilities, which adds some context beyond basic purpose. However, it lacks critical details such as whether this is a read-only operation, potential rate limits, authentication requirements, error handling, or the format of returned values. For a tool with 6 parameters and no annotations, this is a significant gap.

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, efficient sentence that front-loads the core purpose and adds filtering context. There is no wasted verbiage or redundancy, making it easy to parse quickly. Every word earns its place by contributing to understanding the tool's functionality.

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 complexity (6 parameters, nested objects in 'matches', no output schema, and no annotations), the description is insufficient. It doesn't explain the return format, error conditions, or behavioral nuances like pagination (implied by 'limit' parameter) or how filtering works in practice. For a tool with this level of complexity and no structured support, the description should provide more operational context.

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 100%, meaning all parameters are documented in the schema itself. The description adds marginal value by mentioning 'filtering by series selectors and time range,' which loosely corresponds to the 'matches', 'startRfc3339', and 'endRfc3339' parameters. However, it doesn't provide additional syntax, examples, or constraints beyond what the schema already specifies, so it meets the baseline for high schema coverage.

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 tool's purpose: 'Get the values for a specific label name in Prometheus.' It specifies the verb ('Get'), resource ('values for a specific label name'), and domain ('Prometheus'). However, it doesn't explicitly differentiate from its sibling 'list_prometheus_label_names' or other Prometheus query tools, which prevents a perfect score.

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 implies usage context by mentioning filtering capabilities ('Allows filtering by series selectors and time range'), which suggests when this tool might be preferred over simpler queries. However, it doesn't provide explicit guidance on when to use this versus alternatives like 'list_prometheus_label_names' or 'query_prometheus', nor does it mention prerequisites or exclusions.

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