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

With readOnlyHint/openWorldHint already declaring read safety, it still adds context that the annotations don't cover: an empty list has two distinct causes (no receipt yet, up to 24h, or a campaign id not on this account), and the production rate limit is one request per minute. It also names the underlying REST endpoint (POST /api/DRStatus), which is unusually concrete.

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 sentences: the shape of the result first, then scoping, then the two operational caveats (empty results and rate limit). Each sentence adds a new fact, with nothing repeated from the schema and no filler.

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, the description must carry return values, and it does, listing the per-destination fields. Combined with the empty-list explanation and the rate limit, an agent has everything needed to call this and interpret a blank result; paging details sit in the schema, so omitting them is fine.

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%, so campaign_id, limit, offset and destination are already documented at the schema level, and the description mostly restates them. 'Pass destination to see one number only' adds a small amount about how the result set changes, but it says nothing new about limit/offset beyond the schema, so this is the baseline case.

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+resource (delivery receipts of a campaign) and defines the shape of the result: one entry per destination containing a timestamp, a DeliveryReceiptStatusId and a carrier code. This makes it distinguishable from get_campaign_status, which is a campaign-level operation; get_delivery_status is per-destination.

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 specifies when to narrow the scope (pass destination for a single-number lookup) and when to use paging (offset/next_offset); it also states the prerequisite that campaign_id is the id returned when the message was sent or scheduled. It never explicitly rules out or routes to alternatives such as get_campaign_status or list_replies.

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