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

Annotations already declare this as a read-only, idempotent, non-destructive operation, so the safety burden is lifted. The description adds real behavioral context beyond them: result ordering (newest first) and the returned fields (who and when), which help the agent interpret output without an output schema.

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 short sentences, zero filler. The core behavior and ordering lead, the use cases follow, and the sibling redirect closes — a well front-loaded structure.

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 simple read-only list tool with full schema coverage and no output schema, the description supplies scope, ordering, and returned fields, which is nearly everything needed. Pagination mechanics are left entirely to the schema's limit/offset fields, a minor 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?

Schema description coverage is 100%, so limit, offset, and workspaceId are already documented in the schema, including the pointer to get_status for discovering site IDs. The description adds only the 'one site' scoping, which is already implied by workspaceId, so the baseline of 3 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?

The description states a specific resource and scope: sent emails for one site, ordered newest first, with recipient and timestamp. It also explicitly distinguishes itself from the sibling that handles the opposite direction of the same correspondence flow (list_inbox).

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?

It names concrete use cases ('what did we send', verifying a specific site was contacted) and routes the alternative case — replies received — to list_inbox by name. Both when-to-use and when-to-use-something-else are covered.

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