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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely useful context outside annotations: the 100-credit Tier 4 cost, the POST endpoint, and the SR suffix convention for planet names. It stops short of describing any constraints on the year (range, validity) or the impactful solar-return computation.

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 tight sentences front-load the core definition before the SR suffix detail, followed by three short metadata lines. No sentence is wasted; slightly denser formatting (bracketed metadata lines) is acceptable but not maximally clean.

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 and the input schema is exhaustively annotated, so the description need not explain return values or parameters. It supplies the domain concept (solar-return ACG) and the SR naming convention, which is the key interpretive detail. The main gap is the absence of routing guidance against sibling geo tools.

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 the schema already documents the body fields, timezone handling, ayanamsa, houseSystem letters, fields/precision compact mode, and the required year. The description adds nothing about parameters. Baseline 3 is appropriate when the schema carries the full parameter burden.

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?

Names a specific resource (A*C*G map) and a precise scope: the solar return of a given year, defined as the moment the Sun returns to its natal longitude. It also flags the SR planet-name suffix, which helps an agent interpret output. It does not explicitly distinguish itself from the sibling astroway_geo_acg (natal ACG), leaving the agent to infer the difference from 'solar return'.

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?

Usage is implied by 'for the solar return of a given year' — an agent can infer this is the tool for a solar-return ACG rather than a natal one. However, there is no explicit when-to-use statement, no mention of the natal ACG alternative, and no prerequisites or exclusions.

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