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

Annotations already mark it read-only and non-destructive, and the description adds real behavior: the 8-second wait ceiling, early return on arrival, the re-call-to-keep-waiting pattern, and an explicit trust boundary treating inbound content as data rather than instructions. The injection warning is exactly the kind of context annotations cannot carry.

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?

Four short sentences, zero filler: the wait/return behavior leads, the retry pattern follows, and the safety note closes. Each sentence carries distinct information an agent needs before calling.

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?

An output schema exists, so return values need not be spelled out, and the description covers the wait semantics and the retry pattern fully. The only gap is what the empty/timed-out result looks like, which the agent must infer from 'if none came, call it again'.

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 67%: 'contact' and 'since' are well documented in the schema, and the description reinforces the single-number scope and the 8-second ceiling that maps to timeout_seconds. It does not add meaning to 'since' (the default of last sent text) or explain the 1–8 second range, so it earns no more than the baseline.

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 — wait for a new inbound text from one number — and gives concrete examples (a reply, a verification code). It doesn't name any sibling (e.g., get_conversation or list_messages) as the non-waiting alternative, so the boundary with polling tools is inferred rather than stated.

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?

Gives clear operating guidance: wait up to 8 seconds, return immediately on arrival, and call again to continue waiting — an explicit polling loop. It stops short of saying when to prefer this over get_conversation/list_messages or what to do when no reply is expected.

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