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

Annotations already cover the read-only/idempotent/closed-world profile, and the description adds real behavioral value beyond them: the result is gated to the first hour of the window for free users, the full-window answer lives in the paid report, and it will never return a time outside the doctor window. It stops short of describing error cases or the response shape for the paid path.

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, front-loaded with the core purpose, then the free/paid behavior, then the hard constraint. 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?

With no output schema, the description steps up and names what the free view returns (Lagna, Nakshatra, quality label) and what is paywalled, plus the window constraint. Only the three undocumented numeric params remain 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 50% (latitude, longitude, timezone are undocumented), so the description carries part of the burden. It clarifies the window concept ('doctor-approved window') and the date scope, but adds no format or default detail for the three bare numeric params.

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 ('Best delivery / C-section time') and scopes it precisely ('inside the doctor-approved window on a given date'), which cleanly separates it from the marriage/shubh muhurat siblings. An agent can identify this tool without opening the schema.

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 useful context about the free tier (best slot only in the first hour) versus the paid report, but never names an alternative tool or states when to prefer e.g. shubh_muhurat or vivah_muhurat. Usage is implied rather than spelled out.

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