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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior. The description adds valuable behavioral context beyond those: it defines the parity values (exact/approximate/unavailable), explains that unavailable metrics are intentionally included, and warns to read caveats before relying on numbers. No contradiction with annotations.

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 compact and front-loaded: the main purpose is stated in the first sentence, followed by a terse, well-structured explanation of parity values and the rationale for listing unavailable metrics. Every sentence carries meaning, with no filler or redundancy.

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 list tool with rich annotations and no output schema, the description covers the key semantic output (parity and caveats) and the intentional inclusion of unavailable metrics. However, it omits any guidance on the two parameters, which are undocumented in the schema as well, and it does not describe the result shape or ordering. This leaves moderate gaps for an agent deciding whether and how to call it.

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 must compensate for the two parameters (category, available_only). It does not mention them at all. The parameter names are semantically transparent (category filter, available-only toggle), but no detail is given about valid categories, filtering behavior, or how 'available_only' interacts with the unavailable-metric listing, leaving the agent to guess.

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 action ('List every metric'), a clear resource ('every metric Onvexia knows'), and the distinguishing content ('with its parity and caveats'). This clearly separates it from sibling tools like get_metric_metadata or get_metrics_batch, which fetch details or batches rather than a full catalogue.

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 explicit usage context: 'check here before asserting that Onvexia can answer a question' and notes that unavailable metrics are listed on purpose. It does not explicitly name alternatives or give 'when not to use' exclusions, so not a 5, but the context is clear enough for a self-contained catalogue tool.

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