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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint=false, yet the description still adds real behavior: newest-first ordering, deleted files excluded, empty list meaning, the exact error payload for an unknown or deleted contact, and the returned field set. This goes well beyond the safety profile the annotations provide.

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, each earning its place: scope first, then return shape, then edge cases (empty list, deleted files, unknown contact). No filler or repetition of the tool 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?

For a single-parameter read tool with no output schema, the description compensates fully by spelling out the response object, its field types, the empty-list semantics, and the error case. Nothing needed to call it correctly is missing.

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 coverage is 100% and the single contactId parameter is fully documented there, including the UUID/not-a-phone-number warning, so the schema does the heavy lifting. The description contributes only marginally by implying a deleted contact ID also yields an error, which slightly clarifies accepted values.

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 (list the files a customer uploaded) plus the exact provenance (through an upload link from create_upload_link), and names the file types. An agent can distinguish this from sibling listing tools like list_work or search without opening the 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?

The provenance clause ('through an upload link from create_upload_link') implicitly scopes when this tool applies and points at the companion create tool, giving clear context. It stops short of an explicit when-not or a named alternative for other file sources, so it is not a full routing rule.

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