Primary Directions

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

Annotations already establish that this is a safe, read-only, idempotent calculation. The description adds the return shape ('timeline of directed aspect hits') and the age-bound scope, but does not add deeper behavioral context such as method implications or output characteristics beyond what the output schema likely covers.

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 tight sentences, front-loaded with the core calculation and followed by the return shape. There is no wasted prose.

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 complex prognostics endpoint, the description is minimally adequate: it names the technique and result. Because the schema and output schema are rich, it does not need to document every field, but it leaves a meaningful gap around how this tool relates to adjacent prognostics methods.

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 schema already defines the parameters in detail. The description only hints at the maxAge parameter with 'up to a maximum age' and does not clarify the directional key rate or aspect-angle parameters, so baseline 3 is appropriate.

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: calculate primary directions, with the technique variants Ptolemaic or Regiomontanus. It also says what the result is (a timeline of directed aspect hits). It does not explicitly distinguish itself from similar prognostics siblings such as symbolic directions or progressions.

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 guidance on when to use primary directions versus symbolic directions, progressions, profections, or other prognostics tools. The phrase 'up to a maximum age' gives some scope, but it does not say when this tool is the right choice.

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