get-unread-count

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

Description states it returns 'the unread count for the requested scope'. With no annotations, it carries the full burden; it accurately describes the read-only, safe nature of the tool. Could optionally mention that it does not modify state, but the description is sufficient.

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?

Three sentences, zero wasted words. Uses a clear 'Use when' / 'Do not use when' structure that is front-loaded and easy to parse.

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 tool's simplicity (2 optional params, no required), the description fully covers when and why to use it, including return value clarification via 'Returns'. Output schema exists to detail return structure.

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 coverage is 100%, so description does not need to detail parameters. It mentions 'optionally scoped to one mailbox and/or account', aligning with schema. No additional semantic info beyond the schema, but context on the return value adds value.

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?

Description starts with 'Use when: you only need the number of unread messages', clearly stating the verb (get), resource (unread count), and scope. It distinguishes from sibling tools by mentioning 'without listing the messages themselves' and referencing list-messages, search-messages, and get-mail-stats.

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?

Explicitly provides 'Use when' and 'Do not use when' sections, listing specific alternative tools like list-messages and search-messages with respective conditions. This gives clear guidance on when to select this tool over siblings.

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