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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the tool is clearly safe and non-destructive. The description adds value by detailing what the tool returns (exact date, time, direction, sidereal longitude, zodiac sign), which goes beyond the minimal annotation and addresses key behavioral expectations.

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 reasonably concise at three sentences plus a keyword list. The first sentence clearly states the core function, with subsequent sentences adding helpful domain context (node directions, crossing frequency, return fields). The trailing keyword list is slightly redundant but does not harm conciseness significantly.

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 that the input schema is comprehensive (100% coverage, 4 parameters with detailed descriptions) and annotations fully cover safety (read-only, non-destructive), the description completes the picture by explaining the astronomical concept, return fields, and unique value proposition. No output schema exists, but the description lists return fields, mitigating that gap.

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?

Input schema has 100% coverage, already describing all four parameters with fairly detailed descriptions. The description does not add new parameter-level details (e.g., it doesn't elaborate on timezone, compact, or coordinateSystem), so it adds no extra semantic value beyond the schema's baseline.

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 clearly states the verb ("Find") and resource ("ecliptic plane crossings for visible planets"), and differentiates from siblings by specifying this is about ecliptic crossings—unique among sibling tools that focus on astrology charts, dashas, or aspects. The inclusion of concept definitions (ascending/descending node) further clarifies purpose.

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 explains key domain context (when crossings occur, e.g., Moon ~2 times/month, outer planets less), but does not explicitly say when NOT to use this tool (e.g., when to use other positional tools like planetary_positions or transit). This implicit guidance is strong but lacks exclusionary advice or alternative tool references.

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