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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavioral context beyond annotations: the data-privacy boundary (which data is excluded from the view, including customer details, message bodies, and internal notes). This scope limitation is valuable for an agent handling sensitive inbox data and complements rather than contradicts the 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 tightly written: the core purpose is front-loaded, followed by what the view receives, then the privacy boundary. Every sentence earns its place. The five-item negative list is slightly lengthy, but it conveys an important privacy constraint that justifies the space. No filler or repetition.

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 0-parameter tool with an output schema present (so return values need not be spelled out), the description covers what it does, what data it exposes, and what it excludes. The only gap is explicit sibling differentiation, which is mild given the tool's simplicity. An agent has enough to call it correctly.

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?

With 0 parameters, schema coverage is trivially complete and there is nothing to clarify. Per the rubric baseline for 0-param tools, a 4 is appropriate: the description correctly focuses on what the tool does rather than inventing parameter details that don't exist.

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 ('opens', 'reports'), resource (metadata-only Supovia inbox), and precise scope (how many conversations have unread activity). The negative-space list ('never receives message bodies, previews, message ids, customer details, or internal notes') actively differentiates it from siblings like list_conversations and get_unresolved_conversation_counts. An agent can tell exactly what this tool is and is not without opening the schema.

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 a workflow ('needed for an explicit follow-up') and clarifies the tool is a metadata-only counter of unread activity, which suggests when it applies. However, it never names sibling alternatives or states explicit exclusion conditions, such as 'use get_unresolved_conversation_counts for pure aggregate counts' or 'use list_conversations for detailed conversation access.' Given the overlapping sibling set, explicit routing guidance would strengthen this dimension.

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