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

Annotations already establish the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lowered. The description adds real value beyond them by disclosing the computation basis: festivals are dated by the tithi at sunrise in India (IST), which affects how the results should be interpreted. It still says nothing about result freshness or caching.

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 sentences with no filler; the resource and scope are front-loaded and the parameter's allowed values are attached compactly at the end. Every clause earns its place.

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 an output schema present, return values need not be explained, and the description covers what is produced, the time window, the calendar convention, and the parameter values. Only minor gaps remain (default horizon behavior, no sibling routing).

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?

The single horizon parameter has 0% schema description coverage and no enum constraint, so the schema alone leaves the agent guessing. The description compensates by enumerating the accepted values ('week' or 'month'), which is exactly the missing information. It does not cover the default or the exact date boundary used.

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 resource (Hindu festivals and observances/vratas) with a defined scope (coming week or month) and the dating rule (tithi at sunrise, IST), so the agent knows exactly what comes back. It never names or contrasts itself with siblings like panchang or monthly_forecast, so it falls short of a 5.

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?

The description ties the tool to a 'coming week or month' window, which implies when it is useful, and the horizon parameter hints at the two modes. There is no explicit when-to-use/when-not guidance and no routing against panchang or monthly_forecast, which is the most plausible confusion set.

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