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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description's genuine contribution is the non-annotated billing context ('10 credits, Tier 1'), which is real added value, but it omits what inputs are mandatory and what the response contains.

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?

It is short and front-loaded with no filler, so nothing is wasted. However the brevity is under-specification rather than efficiency, since two lines cannot carry the burden of a 15-parameter chart calculation.

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, 4-required-parameter chart tool with an output schema and a near-identical sibling, this definition leaves the agent without the information needed to invoke it correctly. Credit cost is disclosed, but input expectations and sibling selection are absent.

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?

The schema has 15 parameters with only ~33% description coverage, so the description carries a heavy burden to compensate. It says nothing about the required date/time/latitude/longitude inputs, the timezone vs timezoneOffset precedence, the 'fields'/'precision' compact mode, or any enum meaning. Zero parameter value is added.

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 the artifact produced (the Spirit-Fortune / Daimon-Tyche axis) and frames it as a 'primary chart spine', which is more concrete than the bare title. But there is no verb (compute/return) and no differentiation from the near-duplicate sibling astroway_helg_daimon_tyche_axis, which appears to be the same technique in a sibling group. An agent can guess the topic but not the action or how it beats the sibling.

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 statement of when to use this tool, what conditions select it, or which alternatives exist. Given the presence of an almost identical helg_ sibling, guidance on when to prefer this variant would be especially valuable, and none is offered.

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