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

Annotations already declare this a safe, idempotent, closed-world read, so the safety burden is covered; the description adds real behavioral context by disclosing that Moon and Rising layers only activate when birth time and location are supplied. It also frames the response stance ('constructive strengths and mindful growth areas'). It does not disclose degradation behavior when only one person's time/location is given, which is the main remaining behavioral gap.

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?

Three sentences: method and scope first, conditional data depth second, output framing third. No filler, no restatement of the title, and the most important routing information is front-loaded.

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 13-parameter tool with a fully documented schema, strong annotations, and no output schema, the description covers purpose, methods, conditional input requirements, and the flavor of the return. The only missing piece an agent might want is guidance on partial data (one person's time known, the other's not) and whether the coordinates/timezone must be supplied as a complete set.

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 100%, so the baseline is 3, but the description adds meaning the schema lacks: it explains why latitude/longitude/timezone/birth_time exist collectively — they gate the Moon and Rising computations rather than being incidental data. It adds nothing about person names or relationship_type, but the enum options are self-explanatory in the schema.

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 ('Analyze multi-layered compatibility between two people') plus the exact methods used ('Pythagorean Life Path numerology and Western tropical Sun signs'), which cleanly separates it from sibling single-person tools like get_birth_chart, get_transits, and calculate_numerology. An agent can identify the two-person relational scope without opening the schema.

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 conditional clause 'If exact birth times and locations are provided, incorporates Moon emotional resonance and Rising ascendant dynamics' tells the agent when to supply the six optional location/time parameters and what depth they unlock. It gives clear usage context but never routes the agent away from adjacent siblings (e.g., get_birth_chart for a single person's chart), so it stops short of explicit alternatives.

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