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

Annotations already establish read-only, idempotent, non-destructive behavior, so the bar is lower. The description still adds real value: it discloses the computed behavior (three-level cascade) and the cardinality of the result (9 PDs of the AD), plus cost (20 credits, Tier 2), none of which is in the annotations or 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?

Two front-loaded sentences that state definition and computation, followed by compact metadata (group, endpoint, cost). No filler; the hierarchy explanation earns its place. Very slightly terse on routing, but nothing is wasted.

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-shape detail is not required, and the description still summarizes the result (9 PDs) and the computation path. Combined with 100%-covered input schema and full annotations, an agent has everything needed to call it correctly.

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%, and the body schema carries extensive field-level documentation (birth data, timezone handling, ayanamsa, compact-mode fields/precision). The description adds nothing about the three parameters, which is acceptable when the schema does the work. Baseline 3.

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 a specific verb+resource ('Pratyantardasha (sub-sub-period)') and pins its position in the dasha hierarchy with the cascade 'find current MD → AD → return 9 PDs of that AD'. That level specification distinguishes it from the vimshottari_antar, prana and sookshma siblings. It stops short of naming any sibling explicitly, so it lands just below the top band.

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?

'3-level cascade: find current MD → AD → return 9 PDs of that AD' conveys implied context (you want the PD sub-level within an already-running AD), but never states when to pick this over vimshottari_antar or vimshottari_prana, nor any prerequisite about knowing the current AD. Usage is inferable 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.