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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real value beyond that: it discloses the computation reference time (12:00 local unless a time is given), explicitly states what is not returned, and gives a data-handling assurance that birth details are used only for this answer and not stored.

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?

Three tight sentences with the resource definition front-loaded, followed by the calculation-time caveat, then scope exclusions and the privacy note. No sentence is filler, and nothing is buried.

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?

With no output schema, the description usefully enumerates the returned panchang elements, states the computation time basis, and rules out commonly expected fields like sunrise/sunset. It stops short of describing output shape or ordering and does not mention the 1900–2099 date bound or place_token expiry, which live only in the schema.

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 100%, so all three parameters are already documented, including the 12:00 default and the place_token provenance. The description's 'calculated at 12:00 local time unless a time is given' restates the schema default rather than adding new meaning, so the baseline of 3 applies.

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 enumerates exactly what the tool computes (weekday, tithi, paksha, nakshatra, yoga, karana) for a date and place, which is far more specific than the title 'Panchang for a day'. It also defines negative scope by excluding sunrise, sunset and Rahu kalam, though it does not name a sibling tool to differentiate against.

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 implied by the enumeration of panchang elements and the date/place framing, and the exclusion of sunrise/sunset/Rahu kalam tells the agent when this tool is insufficient. However, there is no explicit when-to-use guidance relative to siblings such as chart_overview or birth_time_check, and no statement that place_token must come from find_birthplace.

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