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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds real value beyond that: 'no messages are sent', the single-page (no auto-pagination) behavior, account-time-zone date semantics, and a prompt-injection warning about treating message text as untrusted.

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, front-loaded with purpose, then constraints, then a safety note; nothing is redundant. Minor cost is that the terse style borders on telegraphic (e.g., 'GET /v2/sms. Read-only.').

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 an 8-parameter search tool with no output schema, the description covers purpose, pagination limit, and safety, but omits how the parameters combine to filter results. An agent can call it, but without confidence about filter semantics or result shape.

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?

Zero schema description coverage across 8 parameters, so the description must carry the burden — yet it only clarifies that dates use the account time zone. Nothing is said about search scope, status enum meaning, source vs destination, or the limit/offset pagination semantics.

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 first sentence names a specific verb (search) and resources (outgoing history, scheduled messages, delivery states), and the endpoint GET /v2/sms anchors it. It is clearly distinguishable from the singular smsglobal_get_outgoing_message sibling.

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 implies the tool is for reviewing/filtering history and notes the 'one page' constraint, which sets expectations. But it never states when to use this list tool versus smsglobal_get_outgoing_message for a single message, leaving that routing to inference.

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