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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. Beyond that, the description adds useful context about output components (shadow dates, signs in both zodiacs, Sun conjunction), the default behavior when no year is supplied, and the cycle frequency (about every 19 months for six weeks). It does not fully explain pagination or response shape, but no output schema exists and the important behavioral notes are present.

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 front-loaded with use cases and return contents, and every sentence largely earns its place. The final reassurance ('Say it without fear...') is stylistic rather than strictly selection-critical, keeping it just below the highest score.

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 no output schema, the description carries the burden of explaining what is returned, which it does: periods, shadow dates, signs in both zodiacs, and Sun conjunction dates. It also covers prerequisites (none) and cadence, making it complete for this tool's complexity.

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 coverage is 100%, so the year parameter is already documented. The description adds meaning by stating the default behavior: with no year it returns the period running now or the next one, while specifying a year lists every Venus retrograde touching that year. That is value 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?

The description states a specific subject and resource—Venus retrograde dates—and enumerates the exact questions it answers, including 'is Venus retrograde now' and 'Venus retrograde 2026'. It implicitly distinguishes itself from nearby planetary tools like mercury_retrograde and saturn_return_dates by focusing solely on Venus.

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 gives explicit triggering conditions and example phrasings, and explains that the tool needs no birth details or place. This is exactly the when-to-use guidance an agent needs, with alternatives implicitly excluded by the Venus-specific scope.

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