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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes well beyond them: it describes the depth of output (mahadasha down to sookshma), how on_date shifts the result to past/future days, how mahadasha expands to all nine antardashas, and that birth_time must be exact. That is substantive behavioral context, especially valuable with no output schema.

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?

Front-loaded with the when-to-use triggers and quoted queries, then output shape, then parameter behavior, then the sibling alternative and prerequisites. Dense but no sentence is 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?

For a read-only astrology calculation with no output schema, the description covers trigger conditions, return content and nesting depth, parameter effects, the sibling disambiguation, and required birth data. Nothing an agent needs to invoke it correctly is missing.

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 five parameters including the enum-bound mahadasha are already documented in detail. The description largely restates the on_date and mahadasha semantics rather than adding format or edge-case detail beyond the schema. Baseline 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 opens with a concrete use case set (mahadasha/antardasha, timeline, start/end dates) and states exactly what is produced: 'Returns every mahadasha with dates, and the antardasha, pratyantar and sookshma running now.' It also explicitly distinguishes itself from the sibling mahadasha_meaning, so an agent can route between the two without inspecting schemas.

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?

It gives explicit triggering user phrasings ('when does my Rahu dasha end', 'which dasha was I in during 2019') and names the alternative for the adjacent case: 'For what a dasha means in general, without birth details, use mahadasha_meaning.' Prerequisites (birth date, time, town) are stated up front.

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