Yogas: Surya (Vesi, Vasi, Ubhayachari)

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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, and the description still adds real context: it states the counting rule excludes Rahu/Ketu and warns 'no result text', telling the agent the response is structured data without interpretation. The 20-credit cost is also disclosed. It stops short of saying what the output payload looks like.

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?

The first sentence is dense but front-loaded with the yoga definitions and the exclusion rule, and the bracketed metadata block is compact. Slight terseness ('Vasi (12th)', 'Ubhayachari (both)') assumes the reader can reconstruct the rule from context, but nothing is wasted.

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 the description's 'the yoga and the planets that form it; no result text' usefully frames the output. However, for a 13-parameter chart computation at 23% schema coverage, the description leaves too much parameter behavior unaddressed to be complete.

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?

With 13 parameters and only 23% schema description coverage, the description carries a compensation burden it does not meet: it only restates the four required parameters (date, time, latitude, longitude) and says nothing about ayanamsa choice, timezone/timezoneOffset interaction, zodiacType, houseSystem, or cosmogram, several of which are undocumented in the schema too.

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 exact resource (the three Sun-based yogas Vesi, Vasi and Ubhayachari), gives the BPHS 38.1 citation, and defines each yoga's formation rule precisely, including that Rahu/Ketu are excluded. 'Counted from the Sun' cleanly separates it from the Moon-based (chandra) sibling without needing to name it.

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 only implied: an agent can infer this is the tool for Sun-referenced yogas, but there is no explicit when-to-use, when-not, or pointer to alternatives such as the 'full' Parashara yogas tool that aggregates all yogas. The cost line and required-parameter line are operational metadata, not selection guidance.

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