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

No annotations are provided, so the description carries the full burden. It discloses the computation basis (planetary degrees), the two karaka families, and the JSON return payload with named fields — useful context. It omits dependency/prerequisite behavior, whether results are deterministic, and whether it fetches chart data itself.

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 WHEN TO USE / WHAT IT DOES / RETURNS headers make it scannable and front-loaded, with no filler sentences. The RETURNS block is slightly redundant given an output schema exists, but the overall structure is efficient.

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?

For an 8-parameter tool with zero schema documentation and no annotations, the description leaves the most important question unanswered: whether the datetime is the birth moment or the current moment, and what the location/timezone defaults mean. Having an output schema excuses it from explaining returns, but the input story is materially incomplete.

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?

Eight parameters with 0% schema description coverage, and the description says nothing about any of them. The four required fields (year/month/day/hour) are ambiguously birth data vs. query time, and the India-centric latitude/longitude/timezone defaults are never surfaced. It does not compensate for the coverage gap.

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 a specific verb+resource ('Calculate Chara and Sthira Karakas') and explains both variants — variable significators from planetary degrees vs. fixed significators. It never names a sibling tool or distinguishes itself from calculate_birth_chart, calculate_yogas, etc., so it falls short of the 5 bar.

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?

'WHEN TO USE: When an agent needs to identify the key planetary significators in a chart for specific life areas' gives a genuine trigger condition, which is more than most. But there are no exclusions, no mention of prerequisites (e.g., that planetary longitudes must already be known), and no routing against the many sibling calculation tools.

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