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

Annotations already declare the safe read-only, idempotent, non-destructive profile, so the description does not need to restate that. It adds useful domain behavior beyond the annotations by explaining the heliocentric substitution and Moon exclusion, and it discloses the 20-credit cost.

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 front-loaded and compact: the core calculation is stated first, followed by the key heliocentric exclusions and metadata. Every line adds relevant information without redundancy.

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 15-parameter astrological calculation tool with only 33% schema description coverage, the description is too sparse. It correctly summarizes the chart type but omits parameter guidance that an agent needs to assemble a valid request; the existing output schema means return values need not be explained, but the input side remains incomplete.

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 coverage is only 33% for 15 parameters, and the description adds no parameter-level meaning. It mentions a 'birth moment' but does not explain required date, time, latitude, longitude, timezone, house system, ayanamsa, or compact-mode fields, leaving most of the schema undocumented in prose.

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 specific verb ('Calculate'), resource ('heliocentric planetary positions'), and frame ('Sun-centered', 'given birth moment'). It also clarifies the heliocentric substitution rule (Earth replaces Sun; Moon excluded), which distinguishes it from standard geocentric siblings.

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?

There is no explicit when-to-use guidance, no prerequisites, and no alternatives named. The Group and Cost tags provide context, but the description does not tell an agent when to select this tool over the related specialized charts.

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