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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, and the description is consistent with them ("Read-only") rather than merely repeating them. It adds genuinely new behavior context: the auth capability required (`read`) and the tenant/inbox scoping that limits what can be fetched.

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 with zero filler: identity of the resource first, then return contents, then scope and permission constraints. Every clause carries information an agent needs.

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 present, the description compensates by listing the returned fields (recipients, subject, body, hold reason, status). Auth requirement and tenant scoping are also covered, leaving nothing material missing for a single-parameter getter.

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?

Only one parameter and schema description coverage is 100%, so the schema already documents `draft_id` fully, including its source (mailbuttons_list_drafts). The description adds no syntax, format, or id-range detail for the parameter, so the baseline 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?

Specific verb ("Fetch") plus resource ("one held draft") with an explicit enumeration of what 'in full' means (recipients, subject, body, hold reason, status). The singular 'one' cleanly separates it from the sibling mailbuttons_list_drafts without needing to name it.

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 the operative context for calling it: the result is scoped to the token's customer and inbox set, and the call requires the `read` capability, so an agent knows prerequisites before invoking. It does not state explicit when-not conditions or name an alternative tool, which keeps it short of a 5.

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