Itu Zones Valid On

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

No annotations are provided, so the description carries the full behavioral burden. It discloses that every listed zone is always valid (no validity window), which is meaningful context beyond the schema. However, it doesn't describe return format (though an output schema exists) or any constraints on the date parameter beyond the schema. For a query tool with an output schema, this is adquate but not rich.

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?

Two sentences, front-loaded with the core purpose. The second sentence explains the reasoning and cross-server consistency goal, which is relevant context. No wasted words, though the second clause is slightly verbose.

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?

Given a two-parameter query tool with a rich output schema and no annotations, the description covers the core question and the underlying domain logic (no validity window). It doesn't need to explain return values because an output schema exists. The only gap is lack of explicit distinction from siblings, but the tool is simple enough that this is minor.

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 100%, so the schema already documents both parameters (code: 1-90, on_date: YYYY-MM-DD). The description adds no parameter-level details beyond what the schema provides. Baseline 3 is appropriate when the schema does the heavy lifting.

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+resource: determining whether an ITU zone was valid on a date. The description goes further by explaining the underlying logic (no validity window exists, so all listed zones are valid) and why the tool exists at all, which is more than a bare purpose statement. It doesn't explicitly distinguish itself from siblings like itu_zones_codes_for or itu_zones_lookup, keeping it from a 5.

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 implies when to use the tool (to check zone validity on a specific date) but offers no explicit when-not guidance or alternatives. The note about answering the same questions as other owner-list servers hints at consistency purposes but doesn't route the agent to a different tool for edge cases.

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