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

Annotations already declare readOnlyHint, non-destructive, and closed-world, so the safety profile is covered. The description adds real behavioral scope beyond that: only sent messages are returned and drafts are excluded, which tells the agent what the result set excludes. It does not discuss ordering or result shape, keeping it short of a 5.

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?

A single dense sentence with the sent-vs-draft distinction front-loaded and filtering compressed into a trailing clause. No filler sentences and nothing redundant with the schema.

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 three-parameter, fully documented, read-only lookup with no output schema, the description gives enough to call it correctly and distinguish its scope. Only minor gaps remain, such as result ordering and what fields are returned.

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 limit, channel, and customer_id are already documented in the schema. The description only restates the channel/customer filtering and adds no format or syntax detail (e.g. how customer_id relates to customers.id, or default paging behavior). Baseline 3 applies when the schema does the heavy lifting.

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?

It names a concrete verb and resource ('Find SENT emails/SMS from the communications log') and immediately disambiguates the most likely confusion by excluding drafts. An agent can tell this apart from inbox-reading or draft tools without opening a schema.

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 states available filters ('Filter by channel and/or customer') which implies when the tool is useful, but it never names an alternative sibling (e.g. search_inbox, read_email_thread) or states when NOT to use it. Usage is implied rather than spelled out.

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