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

Annotations already indicate readOnly and idempotent behavior, so the bar is lower, but the description adds significant behavioral context: response structure, out-of-range behavior (temporal_context band and payload_scope), and a caveat about unordered jsonb object keys requiring sorting by spread_pos. This goes well beyond annotations.

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 dense and front-loaded with the primary use case and sibling exclusions before return details. Some listing could be trimmed or structured, but every sentence contributes necessary guidance, and no content is wasted for the complexity involved.

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 a single-parameter tool with no output schema, the description is remarkably complete: it enumerates the use cases, the returned blocks, field details, ordering caveats, and out-of-range behavior. An agent has enough context to invoke the tool correctly and interpret its results.

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 the date parameter fully, including format and scope. The description merely restates that it accepts any Gregorian date, adding no new semantic details beyond the schema.

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?

Description states a specific verb and resource: get the full identity of any single Gregorian date. It explicitly distinguishes itself from siblings by saying it is NOT for two-person scoring (use get_compatibility) or name text (use get_name), leaving no ambiguity.

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 gives a clear, explicit when-to-use list covering specific needs like moon phase, retrogrades, calendars, weekday, and more. It also names the exact alternative tools and the conditions that route elsewhere, which is model guidance.

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