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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered. The description adds the useful facts that the chart can be cast for a location other than the birth place and that this is an API Pro feature, but says nothing about return contents, precision, or failure behavior for unknown times.

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?

A single compact sentence plus a tier tag; nothing is padded or redundant, and the core purpose is front-loaded. It is arguably under-specified rather than over-long, but as structure goes it is efficient.

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 tool with a nested birth object, an optional location override, and no output schema, the description is thin: it never indicates what the returned chart contains or how a missing birth time (documented as suppressing time-dependent values in the schema) affects the result. Annotations cover the read-only/idempotent profile, so the gap is moderate rather than severe.

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?

Top-level parameters (year, birth, location) carry no schema descriptions, though the nested birth object does document date, time, and timezone. The phrase 'cast for the birth place or another location' partially compensates by clarifying that location is an optional override of the birth coordinates, but year constraints and the location shape are left unexplained.

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 product (the solar return chart) and its scope (one year, cast for the birth place or another location), so an agent knows what is produced. It does not, however, distinguish this from closely related siblings like natal_chart or transits, leaving the agent to infer the difference from the name alone.

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 such as natal_chart or transits. The only routing signal is the parenthetical '(API Pro)', which hints at an access tier rather than a usage condition.

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