list_messages

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

Given no annotations, the description fully discloses key behaviors: server-side filtering, field selection with `id` always included, and inclusion of `conversation_id`. It accurately portrays a read-only operation without contradictions.

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 three sentences, each earning its place. First sentence states core purpose, second and third detail parameter usage and output benefit. No redundant information.

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 (not shown), the description covers necessary context: listing from a folder, ordering, filtering, field selection, and threading info. It is adequate for a simple listing tool.

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% schema description coverage, the description adds value by explaining `since` (ISO-8601 format) and `fields` (override columns, id always included). Other parameters (`limit`, `folder`, `account_id`) are not addressed but their defaults are in the 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 clearly states 'List recent mail messages from a folder, newest first.' It specifies the verb, resource, and ordering, differentiating it from sibling tools like `search_messages` or `get_message`.

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?

Provides explicit guidance for the `since` and `fields` parameters, and hints at use cases for threading via `conversation_id`. However, it does not directly compare to alternatives like `search_messages` for complex filtering.

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