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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds useful context — the ordering dependency on send_sms and that the lookup is scoped to the authenticated account — but says nothing about eventual consistency or whether polling is needed for a 'pending' status.

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?

One sentence, no filler, with the precondition (after send_sms) front-loaded before the action. Nothing to trim.

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?

A simple one-parameter read with an output schema for return values and annotations covering the safety profile — the description supplies the missing prerequisite and scope. Only the polling/freshness nuance is absent, which is minor for this tool's complexity.

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 0%, so the description must carry the parameter meaning; it does so only minimally by tying sms_id to the SMS created by send_sms. The single integer parameter is largely self-explanatory from its name and type, so no more depth is strictly needed, but nothing is added about ID sourcing or validity.

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 names a specific verb (fetch) and resource (delivery status of an authenticated account SMS) and identifies the key (sms_id). Referencing send_sms as the predecessor clearly separates it from the sibling that creates SMS, though it doesn't differentiate itself from the other get_* retrieval siblings.

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?

'Use this after send_sms' gives an explicit precondition and context for invoking the tool. No exclusions or when-not-to-use guidance are given, but for a simple status lookup the trigger condition is unambiguous.

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