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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely new context in the credit cost (10 credits, Tier 1) and the endpoint, but says nothing about what is computed, return shape, or any domain-specific caveats for heliacal phase/station calculations.

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, front-loaded, and cleanly delimited with bracketed metadata blocks that are easy to scan. The fault is under-specification rather than bloat, so conciseness itself is handled well.

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, POST-based ephemeris tool in a crowded Hellenistic family, this is not complete enough: the functional statement is four words and the rest is boilerplate (group, endpoint, required, cost). An output schema exists so return values needn't be explained, but the description still leaves the agent without enough to confidently distinguish or correctly invoke this tool.

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 only 33%, so the description should compensate, yet it merely repeats the four required fields already marked required in the schema and adds no semantics for the other eleven parameters. No format, range, or interaction guidance (e.g. timezone vs timezoneOffset) is contributed.

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 a specific astrological resource ('Heliacal phases and stations'), but it is a noun phrase with no verb and largely restates the title 'Stations & Phases'. It gives no indication of what the tool actually computes or returns, and it does not distinguish itself from near-identical siblings such as astroway_hels_stations_and_phases or astroway_hellenistic_schmidt_morning_evening_stars.

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 when-to-use guidance, no prerequisites, and no mention of alternatives, despite dozens of closely related Hellenistic and Schmidt-tradition siblings. The only usage-adjacent content is a restatement of the required parameters, which is not routing guidance.

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