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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds useful behavioral context beyond that: it returns one workspace-sent message with a full timeline of delivered, opened, clicked, bounced, and complained events, and requires an id from prior send/list calls.

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?

The description is two sentences, front-loaded with the usage trigger, and contains no filler. Every sentence contributes either the when-to-use condition or the return behavior.

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 is simple: one required parameter, no output schema, and read-only annotations. The description fully covers what the agent needs: when to call it, what identifier to pass, and what the response contains.

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 covers the single 'id' parameter fully, so the baseline is 3. The description adds extra value by clarifying that the id comes specifically from connections_email_send or connections_emails_list and that it refers to a message this workspace sent.

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 verb ('look up' / 'Returns') with a clear resource: one sent email and its event timeline. It distinguishes itself from send/list siblings by focusing on retrieval of a single message's delivery outcomes.

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 explicitly says 'Use this when the member asks whether an email arrived, bounced, was opened or clicked,' giving a clear trigger condition. It does not explicitly contrast with alternatives, but it references that the id comes from connections_email_send or connections_emails_list, which is helpful routing context.

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