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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds meaningful behavioral context beyond them by pinning the result set to already-sent messages and excluding drafts, though it says nothing about result volume, ordering, or pagination beyond the schema's limit.

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?

Two tight sentences with the scope qualifier (sent, not drafts) front-loaded before the filter capability. 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?

For a 3-parameter read tool with annotations and no output schema, the description covers purpose, scope, and filtering adequately. It could note what the returned communication records contain or how results are limited/ordered, but nothing critical to correct invocation is missing.

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 that filtering is possible by channel and/or customer, adding no format or syntax detail beyond the structured fields — the baseline 3 for full coverage applies.

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?

States a specific verb (find) and resource (sent emails/SMS in the communications log), and explicitly scopes to SENT messages versus drafts awaiting a Send click. This cleanly separates it from inquiry-oriented siblings like search_inbox or read_email_thread.

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?

Gives clear context: it finds sent communications and supports filtering by channel and/or customer. It distinguishes the sent/draft boundary, but does not name an alternative sibling (e.g., search_inbox or read_email_thread) or state when-not to use this tool.

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