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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=false, idempotentHint=false), so the bar is lower. The description still adds real context the annotations do not: 'nothing stored' discloses persistence behavior and 'no predictions' scopes the interpretive output as reflective rather than predictive, which sets an agent's expectation for the returned text.

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 with no filler: the first front-loads what is computed and over what timeframe, the second front-loads the output character and side-effect guarantees. Nothing is repeated, and the densest information (positions, transits, orbs, dates) leads.

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 a 9-parameter tool with no output schema, the description does describe the returned content (planet positions, transits with orbs and exact dates, short interpretation) and the two side-effect facts an agent most needs. It leaves the birth-location/timezone input paths entirely to the schema, but since coverage is 100% that is a minor gap rather than a missing piece.

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% and every parameter (including latitude/longitude/timezone alternatives, birth_time, language) is already documented in the schema. The description only restates the date and period semantics, adding no syntax or precedence detail beyond the structured fields. Baseline 3 applies when the schema does the heavy lifting.

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 names a specific verb-and-resource pair (shows planetary positions and the transits they make to a birth chart) plus the output content (orbs, exact dates) and the timeframe (one day or a 7-day week). It is clearly distinct from sibling tools like get_birth_chart (natal-only) and compare_charts (two charts) without needing to name them.

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?

Usage context is explicit: 'now (or on a given UTC date)' and 'for one day or a 7-day week', which maps directly onto the date/period parameters. However, it never names an alternative tool or states when not to use this one (e.g. versus get_birth_chart for natal-only data), so it stops short of full routing guidance.

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