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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the safety profile is covered. The description adds genuine context beyond that: the computation basis (Swiss Ephemeris, Lahiri ayanamsha, Trikaal Vaani engine), the default location, and timezone handling. It does not cover data volume or response shape, but with annotations present this is solid.

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 primary purpose (eclipses) is front-loaded, followed by transits and the optional Sade Sati behavior. It is dense and long with some run-on sentence structure, but nearly every clause carries substantive information rather than 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 carries the burden of describing return contents, and it does so thoroughly (types, times, visibility, rashi, nakshatra, sutak, stations, rashi parivartan). An agent could invoke it correctly; minor gaps are the absence of sibling routing and confirmation of what an empty/edge case yields.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning beyond the schema: it explains that chandra_rashi unlocks Sade Sati/Dhaiya periods, and clarifies the default-place and timezone semantics. This is more than the enum and defaults already convey.

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 names specific resources (Surya/Chandra Grahan, graha sthiti, gochar calendar) with concrete attributes (type, start/peak/end, rashi, nakshatra, sutak) rather than a vague restatement of the title. It is clear what the tool returns, though the three-in-one scope (eclipses + transits + Sade Sati) is broad and overlaps conceptually with the sade_sati sibling without being explicitly contrasted.

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: the description notes that passing chandra_rashi adds Sade Sati/Dhaiya status, giving a hint about optional invocation. However, it never states when to reach for this tool versus panchang_today or sade_sati, and offers no when-not guidance.

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