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

Beyond the annotations, the description discloses the supported year range, default Polish timezone, minute-level precision, and the extra sign-specific output fields. It does not discuss error behavior or edge cases, but the read-only annotations already cover the safety profile.

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 the core operation and uses only three sentences. It is efficient overall, though the phrase 'With a sign, also its usual first and last day...' is slightly compressed and could be clearer.

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 the rich input schema, output schema, and annotations, the description is complete enough for an agent to call the tool correctly. It covers the main operation, range, timezone default, sign-specific behavior, and the main edge-case use.

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 coverage is already 75%, and the description adds meaningful semantics beyond the schema by explaining what happens when a sign is supplied: usual first/last day and earliest/latest entry across 1900–2100. It also reinforces the year range and timezone default, though it says little about the lang parameter beyond what the schema provides.

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 resource and computation: zodiac sign ingress times for a given year, with minute precision and timezone context. It is clearly not a general birth chart tool, though it does not explicitly name sibling tools or draw sharp boundaries against astro_calendar or birth_chart.

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 a clear use case for edge-of-sign birth-date questions, which helps an agent choose this tool over a broader birth-chart tool. It does not state exclusions or name alternatives, so the routing guidance is useful but not fully explicit.

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