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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds two things those fields do not carry: the operational cost (100 credits, Tier 4) and the shape of the result (all pairwise cross-chart aspect matrices), which tells the agent the output volume scales quadratically with input count.

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?

Two tightly packed lines: the capability statement first, then bracketed group and cost metadata. No filler, no restatement of the title, and the scoping constraint ('2–8 charts simultaneously') is front-loaded where it 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 described, and the cost line covers the main operational unknown. Still, for a tool taking an array of full birth-data objects the description omits that inputs are per-chart natal birth data, gives no guidance against the pairwise sibling, and its 2–8 claim conflicts with the schema's maxItems of 10.

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 coverage is 67% and the description adds nothing about `fields` or `precision`, so it neither compensates nor extends the schema there. Worse, it states a chart range of '2–8' while the schema's inputs array declares minItems 2 and maxItems 10, so an agent trusting the prose would wrongly refuse a 9- or 10-chart request.

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 synastry aspects') plus the distinguishing scope ('among 2–8 charts simultaneously', 'all pairwise cross-chart aspect matrices'), which separates it from the two-chart astroway_relational_synastry sibling. It never names that sibling or any other alternative, so the differentiation is implied by scope rather than stated.

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 says what the tool computes but gives no when-to-use or when-not-to-use guidance: nothing about preferring this over astroway_relational_synastry for a pair, over astroway_relational_synastry_aspect_grid, or over the composite/Davison tools. The credit tier hints at cost sensitivity but stops short of any routing advice.

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