Get Inbox Draft

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

Annotations already declare readOnlyHint true, destructiveHint false and openWorld false, so the safety profile is covered. The description adds meaningful context beyond that: it enumerates what the read returns (recipients, subject, html/text, carried files, reply thread/message), which matters because there is no 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?

Front-loaded with the core action and the key disambiguation, and each sentence carries useful information. Slightly dense with enumerated return fields, but nothing is padding.

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?

Because no output schema exists, the description's enumeration of returned fields (body, recipients, files, reply linkage) supplies the return-value information an agent would otherwise lack. Combined with the ID-provenance hint and sibling contrast, the definition is complete for a two-parameter read tool.

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% and both parameters are documented there, with draftId already pointing to list-inbox-drafts. The description repeats that guidance but adds no syntax or format beyond the schema, 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?

States a specific verb and resource ('Get a draft by ID from a Resend inbox') and distinguishes itself from siblings by name: unlike get-inbox-thread, which lists a conversation without bodies. An agent can separate this from list-inbox-drafts and get-inbox-thread without opening 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 when-to-use ('read a draft back before send-inbox-draft puts it in the mail'), names the contrasting sibling (get-inbox-thread), and routes the agent to the ID source (list-inbox-drafts). Nothing is left to inference.

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