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

Beyond the readOnly/idempotent annotations, the description discloses behavioral details such as 'newest first', 'Returns compact rows', and the default date window. These add meaningful context not available from annotations alone, though no mention of pagination or rate limits is made.

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, each purposeful and front-loaded. No redundancy; the description is succinct yet packs in scope, ordering, return style, an alternative, and behavioral defaults.

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 9-parameter tool with full schema descriptions and an output schema, the description covers purpose, defaults, and relationships to siblings adequately. It could have mentioned pagination explicitly, but the cursor parameter is documented in the schema, so this is not a major gap.

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 already provides 100% parameter descriptions, but the description enhances understanding of date_range by stating the default (last_30_days) and the all_time option, and clarifies that from_date/to_date are for custom ranges. It also implies the output contains ses_message_id, linking to get_message.

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 searches email events, enumerates the event types, and specifies ordering (newest first). It also distinguishes itself from siblings by pointing to get_message for full timelines and implicitly contrasting with email_stats and list_sources.

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?

Explicitly advises when to use get_message instead: 'use get_message with a row's ses_message_id for the full timeline.' It also clarifies the default date window (last 30 days) and how to override it with date_range 'all_time', giving concrete usage guidance.

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