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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the folder set and unread-count specificity, but it does not add much beyond annotations, such as auth needs or return details.

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 one efficient sentence with no waste. It front-loads the read-only marker and states the core behavior and scope immediately.

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 read-only counts tool with rich annotations and no output schema, the description is mostly complete: it names the folders and explains how the target email zone is identified. It could still clarify whether one of the zone parameters is required in practice.

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 carry parameter meaning. It names both `email_zone_id` and `email_zone_uuid` and clarifies that either identifies one email zone, which adds useful semantics beyond the bare 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 states a specific verb/resource: retrieving unread message counts per folder for one email zone. It is clear what the tool returns and its scope, though it does not explicitly distinguish itself from nearby email-related siblings.

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?

It does not say when to use this tool versus alternatives such as list_email_messages, get_email_message, or get_email_thread. The usage is only implied by the phrase 'Unread message count per folder,' with no explicit guidance or exclusions.

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