list-messages

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

No annotations exist, so description must carry full burden. It describes return fields (id, date, subject, sender) and mentions diagnostics for skipped mailboxes. However, it does not explicitly state read-only nature, auth requirements, or side effects. With zero annotation coverage, more behavioral context would be prudent.

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?

Succinct and front-loaded: starts with 'Use when', each sentence adds value. No redundant or vague statements. Efficient use of words.

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 presence of an output schema, the description still explains return format (fields and diagnostics). It covers usage scenarios, parameter roles, and how it integrates with sibling tools. Complete for a listing tool with six parameters.

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% with descriptions. The description adds meaningful context: explains pagination (limit/offset), filtering by sender and unreadOnly, and optional mailbox vs. all mailboxes. It does not mention the 'account' parameter but covers the primary functional parameters well.

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 the tool lists recent messages from a mailbox with optional filters (sender, unreadOnly) and pagination. It differentiates from siblings: search-messages (for specific criteria) and get-message (for body by ID). The verb 'browse' and resource 'recent messages' are precise.

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?

Explicit 'Use when' and 'Do not use when' sections with concrete alternatives. It specifies pagination via limit/offset, obtaining IDs for other tools, and when to use search-messages or get-message instead. No ambiguity.

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