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

Annotations already cover read-only/idempotent/non-destructive, and the description adds real value on top: no language model is invoked, output is deterministic, pricing is 5 credits with only successful calls charged, and a sandbox key returns a fixed free sample. This is exactly the behavioral context structured fields do not carry.

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?

Purpose is front-loaded, followed by tight one-line cost and determinism statements and a single worked example. Slightly long, but every line (credits, sandbox behavior, determinism) earns its place.

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?

With annotations and an output schema already present, the description's remaining burden is behavioral and cost context, which it covers well, plus a callable example. The only real gap is sibling routing, which a complex multi-prediction platform arguably warrants.

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 both parameters (including the 15-value domain enum and the nested birthData fields) are already documented. The worked example argument adds a concrete, callable shape but no semantics beyond what the schema provides, so 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?

States a specific verb and resource ('Deterministic reading of one life domain') and enumerates what the reading contains (verdict, factors, timing windows, method agreement, corpus position). It does not name any sibling it is distinguished from, so an agent still has to infer how it differs from get_guidance, get_forecast or get_chart.

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 description never says when to choose this tool over the twelve siblings, nor does it state prerequisites or exclusions beyond the domain enum. The cost line and example hint at context but give no routing guidance.

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