get_big_three

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

Annotations already declare the operation read-only, idempotent, and non-destructive. The description adds valuable behavioral context beyond that by specifying how the Ascendant should be handled when birth time is missing, which is a real edge case an agent needs to know.

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 sentences, no filler. The primary purpose is front-loaded, and the edge-case instruction is concise. Every word serves a purpose.

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?

Given the output schema exists and annotations cover the safety profile, the description is largely complete. It handles the key complication of missing birth time. The only slight gap is the vague reference to the 'GetBirthChart contract' and the lack of explicit sibling alternatives.

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 71%, with latitude and longitude lacking descriptions. The description compensates meaningfully by connecting birth time/unknown_time to the Ascendant behavior, which is not inferable from the schema alone. Other parameters are self-explanatory by name and schema descriptions.

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 states a specific action — 'Calculate the Sun, Moon, and Ascendant for a birth chart' — and clearly identifies the resource and scope. It is clear, though it does not explicitly contrast this tool with siblings like calculate_birth_chart or get_moon_sign, so differentiation is left to inference.

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 provides a meaningful usage rule: if birth time is unknown, do not guess the Ascendant and instead return it as unavailable. However, it does not say when to prefer this tool over alternatives such as calculate_birth_chart, so sibling routing is only implied.

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