list_mail_messages

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 two useful behavioral facts beyond annotations: reads do not mark messages as read, and results are ordered newest first. This is meaningful context for an agent deciding whether to call this tool.

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?

Two sentences with no waste. The purpose is front-loaded, then scope/order, then a behavioral note and the key sibling pointer. Every sentence earns its place and the structure is ideal for an agent scanning quickly.

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 list tool with no output schema, the description covers the essential return type ('message summaries'), ordering, default folder, and the read-only behavior. It doesn't mention pagination or cursor usage, but the schema documents cursor and its pattern, so an agent can infer it. Given the low complexity and rich annotations, this is nearly complete.

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 schema covers cursor and folderId with descriptions, leaving limit undocumented. The description adds no parameter-level detail beyond the default inbox, which is already in the schema's folderId default. With 67% coverage, the description does not compensate for the missing limit semantics, but limit is self-explanatory (integer with min/max). Baseline 3 is appropriate.

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?

States a specific verb and resource: 'List message summaries from your own Outlook folder' with explicit ordering 'newest first' and default scope 'inbox'. It clearly distinguishes itself from the sibling read_mail by noting that full bodies require that tool, so an agent can tell them apart without opening schemas.

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 when to use it (for summaries) versus read_mail (for full bodies), and clarifies the default folder behavior. It does not mention search_mail or list_mail_folders, but the core alternative (read_mail) is explicitly addressed, giving an agent clear context for typical usage.

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