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

With no annotations, the description carries the full behavioral burden. It discloses that birth time is required and that other vargas return not_available, which is useful limitation context and does not contradict any structured field. It omits auth/rate-limit details, but for a read-only chart calculator those are likely non-issues.

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?

Single compact paragraph, front-loaded with the chart type and supported vargas, then prerequisites and limitations. Every clause adds relevant information with no filler.

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?

The tool has 9 parameters, 0 required, and an output schema, so some omissions are tolerable. The description covers varga selection, the time prerequisite, and unsupported-varga behavior, but it does not explain how place, ayanamsa, or chart_id/geonameid should be used, leaving key input context missing.

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 11% (just utc_offset) across 9 parameters. The description mentions varga selection and the birth-time requirement, but leaves date, place, lang, ayanamsa, chart_id, and geonameid undocumented, so it fails to compensate for the sparse schema.

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 it computes a divisional (varga) chart, lists the exact supported vargas (D2, D3, D7, D9, D10, D12), and notes that the varga parameter selects among them. It implicitly distinguishes itself from natal_chart by scope, but does not name a sibling tool for explicit differentiation.

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?

Gives the precondition that birth time is required and states that unsupported vargas are not calculated (return not_available), which sets expectations. However, it does not say when to choose this over natal_chart or how it relates to ashtakavarga or other sibling tools, leaving usage context implied.

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