list_emails_metadata

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

With no annotations, the description fully carries behavioral disclosure. It reveals that only metadata is returned, explicitly excludes preview/body-derived content, and describes the conditional JSON envelope format. This is substantial, actionable behavioral context.

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 well-structured and front-loaded. It opens with the core comparison, then details fields, exclusions, use cases, and response format—every sentence earns its place with no filler.

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?

Despite having no output schema, the description thoroughly compensates by explaining the response envelope and array fallback. It covers use cases, exclusions, and related tools, making the description complete for a list tool with optional 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 description coverage is 100%, so the schema already explains limit, ascending, and mailboxId. The description adds only a generic mention of 'paging and sort' and 'optionally filtered by mailboxId', which does not materially exceed the schema. 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?

The description clearly states that this tool lists emails but returns only metadata fields, explicitly contrasting with list_emails. It lists the exact fields returned and what is excluded (preview/body content), making the purpose unambiguous and distinguishing it from sibling tools.

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 explicitly recommends use in privacy-sensitive flows and names get_email_metadata as a companion tool for header-only follow-ups. This is strong guidance on when to use the tool and how it relates to alternatives.

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