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

With no annotations, the description carries the full burden and does so well: it discloses the mandatory birth-time requirement, the reason for it, exactly what the tool returns, and the not_available response behavior for unsupported vargas. This gives an agent a concrete model of the tool's behavior.

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 description is compact, front-loads the purpose, and uses typographic emphasis (caps, emoji) for important constraints. It is slightly longer than a minimal statement, but the added sentences about the varga parameter and not_available behavior earn their place in an annotation-free definition.

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 8 parameters, no annotations, and no schema descriptions, the description covers the critical decision points: supported vargas, required birth time, returned values, and unsupported divisions. The existence of an output schema and self-explanatory parameter names covers most of the remainder, though exact input formats are not stated.

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 0%, so the description must compensate. It adds real meaning for varga (selection among supported divisional charts) and highlights the birth-time dependency, but leaves date, place, geonameid, chart_id, and ayanamsa semantics to be inferred from names/enums rather than explained.

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 (varga/fractional chart), enumerates the supported divisions (D2, D3, D7, D9, D10, D12), and states the one-tool-per-varga design plus the returned contents (varga lagna, planetary placements, vargottama list). This makes it easy to distinguish from natal_chart and other astrological siblings.

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?

It gives clear preconditions: known birth time is mandatory because the varga lagna cannot be derived without it, and unsupported divisional charts should not be computed manually but reported via not_available. It does not explicitly name sibling alternatives (e.g., natal_chart or what_we_calculate), so it falls short of full alternative routing.

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