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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so safety is covered. The description adds genuine domain behavior beyond that: the cycle starts from the lord of the Moon's nakshatra, the first period is truncated by the elapsed fraction, and it carries cost/tier metadata (20 credits, Tier 2). It does not address caching or output volume, so it stops short of a 5.

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 compact sentences front-load the definitional facts, and the cost/group tags are short. Nothing is padded, though the metadata tags are structured data rather than description content and add mild clutter.

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 annotations covering the safety profile and a full output schema, the return format needn't be explained, and parameters are fully covered by the schema. But against a family of several dozen near-identical dasha tools, the description gives no routing cue for the maha versus antar/pratyantar/prana/sookshma levels, which is the main completeness gap.

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%, and the body parameter's nested schema already documents date/time/latitude/longitude requirements, timezone handling, ayanamsa and houseSystem constraints in detail. The description adds no parameter meaning of its own, so the baseline 3 for schema-covered params is appropriate.

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 the specific system (Vimshottari Mahadasha), its 9-planet sequence, 120-year cycle, and starting rule, which is enough to tell it apart from other dasha systems like yogini_maha or ashtottari_maha. However, it never explicitly says what the tool returns (the mahadasha period timeline) nor distinguishes itself from the level-siblings vimshottari_antar/pratyantar/prana/sookshma, leaving that inference to the reader.

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 when-to-use or when-not guidance. It does not tell the agent to pick this for the major-period level versus the antar/pratyantar/sookshma Vimshottari variants, nor when Vimshottari is preferred over other dasha schemes. Neither exclusions nor alternatives are mentioned.

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