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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is low, and the description still adds real behavioral context: the orb model used (per-pair astro.com matrix) and the cost (10 credits, Tier 1). It omits any auth or rate-limit notes, but the orb provenance is meaningful added value.

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 tightly written sentences that front-load the core purpose and then the differentiator, with group/cost metadata kept to bracketed tags. Nothing is padded, though the cost line is boilerplate rather than tool-specific guidance.

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?

An output schema exists, so return values need not be explained, and the description does cover what the tool produces. The gap is on the input side: for a 15-parameter tool with 33% schema coverage, the description leaves most parameter meaning and several sidereal/house-system choices undocumented.

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?

With 15 parameters and only 33% schema description coverage, the description must compensate for the undocumented inputs, yet it names none of them (date, time, latitude, longitude, ayanamsa, houseSystem, zodiacType). The only field list it gives (type/exactAngle/orb/isApplying) describes the output, not the parameters.

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?

States a specific verb and resource (aspect calculation) and enumerates the returned aspect fields (type, exactAngle, orb, isApplying). It clearly distinguishes itself from the full chart endpoint, but does not differentiate itself from sibling aspect tools like astroway_aspects_aspect_bar or astroway_aspects_parallel_aspects.

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 clause 'same calcAspects() as /chart but without planet positions / houses / midpoints overhead' implies you should use it when you only need aspects, which is a usable hint. However there is no explicit when-to-use vs when-not-to-use statement and no mention of the many sibling aspect tools an agent could pick instead.

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