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

The annotations already establish that this is a read-only, idempotent, non-open-world operation. The description adds useful domain behavior beyond that: the Moon is explicitly excluded, planetary scope is Sun through Pluto, only five major aspects are included, and each result carries an exact date and retrograde status. It stops short of describing the full return shape or error behavior.

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 two dense but efficient sentences. It front-loads the core purpose and scope, then gives the aspect list and exclusions without wasted text.

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 detailed input schema and read-only annotations, the description is nearly complete for invocation. It explains what is computed and what output fields matter conceptually, but without an output schema it does not fully specify the return structure or all defaults, leaving a modest 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?

Schema description coverage is 100%, so the input schema already documents all eight parameters, including birth date, span controls, location, timezone, and time. The description does not add parameter-level meaning beyond the schema; it only alludes generally to a span and the chart being targeted.

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 scope: exact transits of Sun-to-Pluto planets to a birth chart's planets, Ascendant, and Midheaven over a span. It is clear what the tool computes, though it does not explicitly distinguish itself from siblings such as progressions, synastry, or returns.

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 is implied by the phrase 'over a span' and by the transit-to-birth-chart framing, but the description gives no explicit when-to-use, when-not-to-use, or alternative sibling guidance. It does not say, for example, when to choose this over progressions or synastry.

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