Natal chart

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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the safety bar is met. The description adds genuine behavioral context: graceful degradation when time is omitted (no angles or houses), the default house system, and the Placidus fallback inside the polar circles. It stops short of stating validation errors or precision caveats.

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?

One dense output-defining sentence followed by a short caveat sentence; every clause carries information and the most important content (what the chart contains) is front-loaded. No filler or redundancy.

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 no output schema, the description bears the burden of explaining return contents and does so thoroughly, including the degraded no-time case. The main remaining gap is that the schema/description interact only loosely on timezone-vs-city precedence, but that is covered by the parameter descriptions themselves.

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 all seven parameters are already documented in the schema, including the city shortcut, coordinate conventions, and house_system enum with its polar fallback. The description adds only the no-time behavior, which the schema already states for `time`; baseline 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 ('Cast a tropical natal (birth) chart') and enumerates the exact outputs (planets with sign/degree/house/retrograde, Ascendant, Midheaven, house cusps, aspects with orbs, element/modality dominance). This clearly separates it from siblings like transits and synastry, which compute charts for other reference frames or pairs.

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 the name and the closing note that the tool still works without a birth time, which tells the agent partial input is acceptable. However, it never names alternatives or states a when-to-use condition relative to siblings such as transits or synastry, so the routing guidance is left to inference.

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