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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the description adds no new behavioral transparency. The description is consistent with the annotations, but does not go beyond them.

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 concise (two sentences), front-loaded with the action and resource, and includes a helpful pointer to the list alternative. No unnecessary words.

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?

Given that the tool is a simple get and there is no output schema, the description provides a reasonable indication of what the response will contain. It could be slightly more explicit about error behavior or exact response structure, but it is sufficient for typical use.

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 only parameter 'id' is described as 'Unique inbox ID.' Schema coverage is 100%, so the baseline is 3. The description does not add extra semantics beyond the field name and short definition.

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 ('Fetch full detail') and a specific resource ('a single inbox by ID'), clearly distinguishing it from inbox_list. The inclusion of expected fields ('email address, display name, associated agent') further clarifies the purpose.

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?

Explicitly differentiates from the sibling tool inbox_list by saying 'Use inbox_list to browse all inboxes.' This gives the agent clear guidance on when to use this tool versus the alternative.

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