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

Annotations already cover readOnly, destructive, openWorld, and idempotent behavior. The description adds the useful detail that the returned link expires in about 15 minutes, but it does not explain permissions, error behavior, or whether repeated calls produce different links.

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 each add a distinct piece of information: UI context, link lifetime, and agent routing to get_attachment. There is no filler, and the key scoping guidance is front-loaded.

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 tool, the description covers usage, expiration, and the sibling alternative. However, with three required undocumented parameters and no output schema, the invocation details are incomplete, leaving a clear gap for an agent that actually needs to call it.

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 has three required parameters with 0% description coverage, and the description never explains inboxId, messageId, or partId. It gives no meaning beyond the parameter names, so an agent cannot tell what these IDs refer to or what constraints apply.

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 identifies a concrete action: it returns a short-lived attachment download link and explicitly distinguishes this tool from get_attachment by telling agents to use the sibling. The purpose is clear, though the phrasing is UI-centric rather than stating the operation as a generic retrieval verb.

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 explicitly limits use to the interactive inbox view when a person clicks Download on an attachment, and it directly tells agents to call get_attachment instead. This provides clear when-to-use, when-not-to-use, and alternative guidance.

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