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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety and repeatability profile is fully covered structurally. The description's only additive behavioral fact is the cost tier (10 credits, Tier 1), which is genuine context not present in the annotations. It says nothing about what the computation depends on, latency, or determinism across different targetAge values, so it goes no further than the metadata block.

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?

Four words of purpose plus bracketed metadata lines — front-loaded but severely under-specified rather than concise. The structure is clean, but the content budget is spent on group/endpoint/cost labels instead of the one thing an agent needs (what the tool does and why targetAge matters).

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 annotations cover the safety profile. What is missing is any statement of what a 'lord of prediction' computation yields for a given targetAge — the required, tool-specific parameter is entirely unmentioned, leaving an agent unable to judge whether this output fits their question. For a specialized Hellenistic tool with a required age input, this is a real gap.

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%: the body schema documents birth data, timezone handling, houseSystem letters, and the compact-mode fields/precision parameters in detail. The description adds nothing about parameters, and most notably never mentions targetAge, the one required field specific to this tool. With the schema doing all the work, the baseline of 3 applies.

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?

'Predictive significator selection' is essentially a tautological gloss on the tool's title 'Lord of Prediction' — it names a topic area but never says what is actually computed or returned. It does not distinguish this tool from its near-identical sibling astroway_hels_lord_of_prediction or from the other schmidt-family tools such as derivative_houses_method or levels_of_causation. An agent cannot tell from this text what makes the tool distinct.

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 named alternative. The only routing aid is the '[Group: Hellenistic: Schmidt tradition]' tag, which is taxonomic rather than actionable. The metadata does state cost (10 credits, Tier 1) and the endpoint, which is mildly useful for budgeting but not for selecting this tool over a sibling.

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