Get Inbox

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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered and the description is not required to restate it. The description adds genuine value by disclosing what a lookup returns (a live snapshot of unread threads, drafts, and last-received time). It does not cover error behavior for a missing inbox, but the gap is minor against the annotation coverage.

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 tight sentences: what it returns, how to supply the identifier, and how to use the result. The return-value enumeration is front-loaded and every clause carries information; nothing is padded or restated from the name.

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?

With no output schema, the description compensates by listing the fields the caller can expect. Combined with the annotations covering the read-only safety profile and the schema covering the identifier, an agent has everything needed to select and invoke this tool correctly.

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% for the single inboxId parameter, including the caveat that it is not the Resend receiving address, so the schema already carries the semantics. The description's 'pass the address directly' guidance adds workflow context but no new parameter detail beyond what is documented, making the baseline 3 appropriate.

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?

Names a specific verb and resource ('Get an inbox') and then enumerates the returned fields (domain, receiving address, timestamps, unread thread count, draft count, last received mail). This distinguishes it clearly from sibling list-inboxes and the many other inbox-* tools without needing to open any 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?

Gives explicit branching guidance: pass the email address directly when the user names the inbox by address, otherwise resolve the ID via list-inboxes. It also states downstream intent ('Use the returned ID with the other inbox tools'), which is exactly the when-to-use context an agent needs.

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