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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is fully covered structurally. The description adds billing context (20 credits, Tier 2) and the required input set, which is genuine decision-relevant information an agent cannot get from annotations. It stops short of describing any behavioral edge cases, such as how the boundary between yoga 27 and yoga 1 is handled.

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?

Extremely compact and front-loaded: the resource identity and formula come first, followed by scannable bracketed metadata. Nothing is wasted, though the terseness comes at the cost of any explanatory prose.

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, so return values need not be explained, and annotations cover safety. But for a 15-parameter astrological computation whose result depends on the ayanamsa choice, the description gives no hint that the sidereal school affects the yoga index, and no routing relative to the panchang_full aggregator.

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 only 33% across 15 parameters, so the description carries a real compensating burden. Instead it only restates the four required fields already listed in the schema's required array, and says nothing about the semantically important optional parameters (ayanamsa, zodiacType, houseSystem, fields, precision) that materially change the longitudes fed into the formula.

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 the specific resource (Surya-Chandra Yoga, one of the 27) and even supplies the computation formula (Sun + Moon longitudes / (360/27)), so an agent knows exactly what is being returned. It does not, however, distinguish itself from a sibling like astroway_vedic_panchang_full, which presumably also yields yoga, so differentiation is left to 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?

The bracketed metadata supplies group, endpoint, required parameters and cost, but nothing states when to pick this tool over astroway_vedic_panchang_full or the other panchang element tools (tithi, karana, nakshatra_of_day). There is no when-to-use or when-not-to-use guidance whatsoever.

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