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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds real payload context — the per-factor shape (raw value, range, frame, rule verdict, rule source, signification ids, timing, birth-time dependence) and the 'no weighting' characteristic — but says little about output size or limits.

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?

Front-loaded with the core purpose, then cleanly sectioned into workflow, input contract, and disambiguation. Slightly dense and the docs URL adds length, but every block carries substantive information.

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?

Output schema exists, so return values need no explanation, yet the description still sketches the factor payload. Combined with workflow, input contract, sibling disambiguation, and an error-contract pointer, nothing needed to invoke the tool correctly is missing.

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 all four parameters; baseline is 3. The INPUT CONTRACT adds only marginal meaning (house_system drives natal_house; target_date/target_timezone defaults), largely restating schema text.

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 gives a precise verb+resource statement ('Every Western factor for one person on one day, in one shape, with no weighting') and enumerates what each factor contains. It explicitly distinguishes itself from sibling tools by name, so an agent can route without opening any schema.

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?

Provides an explicit workflow (BEFORE: get_western_natal; AFTER: get_western_events) plus a 'DO NOT CONFUSE WITH' block naming two siblings and the exact axis of difference (aspects-only vs rules; AI-written text). Strong when-to-use and exclusion guidance.

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