mark_emails_as_read

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

With annotations already indicating mutating (readOnlyHint=false), idempotent, non-destructive, and open-world behavior, the description adds valuable specifics: 'Partial or ambiguous effects report per-ID succeeded/failed/unknown status and are not retried automatically.' This goes beyond the structured annotations by explaining failure semantics and lack of auto-retry, though it does not discuss auth or rate limits.

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?

Three sentences, front-loaded with the core action, then a useful alternative equivalence, a prerequisite, and a concise note on partial/failure behavior. Every sentence earns its place with no redundancy or 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?

The tool has a modest parameter set, clear annotations, and an output schema (signaled by 'has output schema: true'), so the description need not restate return structure. It covers the key workflow step (list first), the behavioral nuance (partial statuses, no retries), and the relationship to set_email_flags, making it sufficiently complete for an agent to invoke correctly.

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 fully documents each parameter. The description adds context by saying 'by email_id' and instructing to use list_emails_metadata first, reinforcing where email_ids come from, but it does not add new semantic detail beyond 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 opens with a specific verb and resource: 'Mark one or more emails as read by email_id.' It clearly distinguishes from sibling tools by noting it is the 'common-workflow equivalent of adding \Seen with set_email_flags,' and references list_emails_metadata as a companion. This leaves no ambiguity about what the tool does.

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 gives an explicit prerequisite: 'Use list_emails_metadata first.' It also names an alternative (set_email_flags) and positions this tool as the common-workflow convenience, implying when to choose it. It lacks explicit 'when not to use' exclusions, but the context is clear enough.

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