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

Annotations already establish readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds that returned contacts include label versus artist ownership annotations, which is useful context, but it does not disclose pagination, authorization nuances, or other behavioral details beyond what the schema and annotations provide.

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 sentence that front-loads the action and resource, then adds the distinguishing output characteristic. There is no repetition of the title or schema details and no filler.

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 read-only list tool with a fully described input schema, an output schema, and safety annotations, the description is nearly complete. The main gap is the absence of guidance on how this relates to sibling contact tools, but the structured metadata covers behavior and parameters adequately.

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 covers all four parameters with descriptions at 100% coverage, so the baseline is 3. The tool description does not add substantial parameter-level meaning; it only hints at ownership scoping through the phrase 'label versus artist ownership annotations.'

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 a specific action ('List contacts') and scope ('across the label family'), plus a distinguishing output trait: label versus artist ownership annotations. It does not explicitly name a sibling tool to differentiate from, but the phrasing is specific enough to separate it from search_contacts or list_contact_lists.

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 a clear context for use: when you need contacts across the label family with ownership annotations. It does not explicitly state when to prefer a sibling like search_contacts or when not to use this tool, but the intended usage is evident.

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