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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds genuine behavioral context: reporting boundary changes, preserving per-convention validation status, and explicitly stating that non-Lahiri full derived systems are not silently recomputed. That last clause is a real behavioral guarantee an agent cannot get from the annotations.

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?

Two dense sentences with no filler, front-loaded on the verb and the selectable conventions. The final sentence about non-recomputation is slightly cryptic in isolation but carries real information.

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 boundary-change/validation notes add useful context. However, with 11 parameters at 27% coverage and a required anyOf branch, the description omits how the coordinate vs. place inputs interact and leaves much of the input contract unexplained.

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 27% across 11 parameters, so the description carries a heavy burden it does not meet. It names the four ayanamsa enum values, but those are already in the schema enum, and it says nothing about the place-vs-coordinates anyOf, date/time formats, or the several undocumented numeric parameters.

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 gives a specific verb and resource ('Projects placements and sign-based Graha Drishti') and scopes it to four named ayanamsa conventions, which is distinctly more specific than most calculate_* siblings. It does not, however, name or contrast with the closest siblings such as calculate_chart_from_known_place or compare_conventions, so differentiation is left to inference.

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?

There is no explicit when-to-use statement, no named alternative, and no guidance on when a different projection tool is preferable. The only hint of usage is the choice among ayanamsa conventions implied by the enumeration, which the agent must infer.

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