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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds real value beyond them by disclosing that only the 'tightest' aspects are returned — a filtering behavior an agent would otherwise not expect — and by restating the input dependency on birth data. It stops short of describing the response shape or how tight the orb cutoff is.

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?

Two sentences, zero filler. The output description comes first and the input prerequisite second, which is the right front-loading for an agent deciding whether it can call the tool.

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 an 8-parameter, 6-required tool with no output schema, the description covers the essential contract: what is computed and what data is required. Minor gaps remain — it does not mention the optional 'place' or 'dst_fold' inputs or clarify the orb threshold behind 'tightest' — but the fully documented schema absorbs most of that burden.

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 every parameter including date, dst_fold, and birth_time is already documented. The description only reinforces that birth data mirrors the natal chart and that a date is added; it adds no format or semantic detail beyond the schema, so the baseline 3 applies.

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?

Names a specific verb and output ('Show where the planets are' plus 'transit-to-natal aspects') and explicitly defines the astrological concept in parentheses. It distinguishes itself from a plain natal-chart tool by referencing 'the same birth data as the natal chart', though it never names get_birth_chart or get_daily_cosmic_weather directly.

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 prerequisite ('Requires the same birth data as the natal chart plus the date to check') tells an agent what inputs are needed, which is genuine usage context. However, there is no explicit statement of when to pick this over get_birth_chart or get_daily_cosmic_weather, and no exclusions or edge-case guidance.

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