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

Annotations only declare readOnlyHint=true, so the description must carry the rest, and it does add real value: the returned fields (mobile, names, messageSent, messageUpdate) and the full status vocabulary (Delivered / Declined / Buffered / Pending with Network / Rejected / Unconfirmed). It does not mention pagination behavior for a report that can return up to 25,000 rows, which is a modest gap.

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: what it returns, how to identify the message, and the vendor endpoint. The identifying information is front-loaded and nothing is redundant or padded.

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 usefully enumerates the returned fields and status values, which is exactly what an agent needs to interpret results. Pagination semantics for the large per-page values are left to the schema, leaving a small gap but nothing critical for correct invocation.

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 description coverage is 100%, so the schema already documents pp, page, message, reference, and subaccount in detail. The description's 'message id OR the custom reference' phrasing essentially restates what the schema already says ('alternative to message'), adding no new syntax or format information, so the 3 baseline 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?

The description gives a concrete verb and resource ('Per-recipient delivery status of one sent message') and enumerates the exact fields and status values returned. It is clearly distinguishable from siblings like firetext_get_click_report, firetext_get_sent_summary, and firetext_list_sent_messages, which cover different report scopes.

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 tells the agent how to identify the target ('Give the FireText message id OR the custom reference used when sending'), which is genuinely actionable. However, it never states when to prefer this per-message report over siblings such as the aggregate get_sent_summary or get_click_report, so the routing guidance is implicit rather than explicit.

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