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

The annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful context that this is low-level and exposes internal naming, but it does not describe output behavior or any special caveats beyond the usage warning. No contradiction exists.

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?

The description is two tight sentences: the first defines what the tool is, and the second provides an explicit routing warning. Every sentence adds value and the warning is front-loaded before alternative recommendations.

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 zero parameters, an output schema, and read-only annotations, the description covers nearly everything an agent needs. The main omission is a positive statement of when to use the tool, but the low-level/internal-naming framing and explicit exclusions make the intended scope sufficiently clear.

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?

There are zero parameters and schema coverage is 100%, so the input schema fully describes the input surface. The description appropriately does not need to add parameter-level detail, matching the baseline for a no-parameter tool.

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 identifies the tool as a low-level endpoint exposing internal provider service codes, which is a concrete resource and differentiates it from the user-facing siblings ucode_sms_summary and ucode_sms_service_detail. However, it does not explicitly state what the tool returns beyond 'internal naming,' so it is clear but not maximally specific.

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 description explicitly warns against using this tool for normal rentals and names the preferred alternatives: ucode_sms_summary or ucode_sms_service_detail, then credits-only packages. This is strong when-not-to-use guidance with direct sibling routing.

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