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

Annotations already mark it read-only and non-destructive. The description adds that results are 'backend USD-ish snapshots' (approximate/stale) and that 'responses are partially sanitized', which an agent needs to temper expectations. This materially extends the structured metadata without contradicting it.

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 short sentences, with the warning front-loaded and alternative tools bolded. Every clause serves routing or caveat purposes; nothing is wasted.

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?

Output schema and annotations already cover return shape and safety, so the description doesn't need to repeat them. It supplies the critical legacy, sanitization, and routing context. The missing parameter semantics is a gap, but the tool is explicitly marked as one ChatGPT users should avoid, so the available context is adequate for selection.

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?

The schema defines country, minutes, and service with no descriptions, and schema description coverage is 0%. The description never explains what values these accept or how they affect results, so the agent gets no parameter semantics beyond bare names.

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 title says 'SMS prices & stock (legacy)' and the description refers to 'backend USD-ish snapshots', so the resource is identifiable. But the description never uses a verb such as 'get', 'list', or 'query'—its main imperative is 'Avoid'—so the actual operation is only inferred, not 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?

The first sentence says 'Avoid for ChatGPT users' and then mandates routing rentals through credits-only tools: ucode_sms_summary, ucode_sms_service_detail, and ucode_sms_rent_packages. This is explicit when-not-to-use guidance plus named alternatives.

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