list_emails

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

The description discloses an important behavioral nuance: the response can be a JSON envelope with total and items when the server reports a match count, otherwise a bare array. This adds valuable parsing context beyond the schema, especially with no annotations present. However, it omits other behavioral details like read-only nature, authentication, or rate limits, which would make it more transparent.

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 highly concise, consisting of two focused sentences. The first sentence states the core purpose, and the second provides a critical detail about response format. Each sentence earns its place with no filler or redundancy.

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?

The tool has no output schema, and the description does not clarify what each listed email contains (full email vs metadata), creating ambiguity given the sibling list_emails_metadata tool. It also does not distinguish itself from search_emails. However, it does cover the core listing action and the response envelope, making it moderately complete for a simple list operation.

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?

All three parameters (limit, ascending, mailboxId) have descriptions in the input schema, giving 100% schema description coverage. The tool description adds no parameter-specific information beyond what the schema already provides, so the baseline score of 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?

The description clearly states the tool's purpose with a specific verb and resource: 'List emails from a mailbox.' It is easy to understand, but it does not explicitly differentiate from sibling tools like search_emails or list_emails_metadata, so it misses the extra distinction that would earn a 5.

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 offers no guidance on when to use this tool versus alternative tools such as search_emails or list_emails_metadata. It simply states what the tool does without any context about typical use cases, exclusions, or comparisons to siblings.

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