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

Annotations already declare readOnly/idempotent/non-open-world, but the description adds substantive behavioral facts: deterministic JPL DE440 computation with no LLM, a per-result meta.result_sha256 for verification, $0.25 per call, the first 3 calls free, and the REST endpoint with x402/MPP payment. That is real added context beyond the annotations.

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?

Purpose and scope are front-loaded in the first sentence, and the enumerations of kootas and outputs are dense but load-bearing. The commercial tail (price, URL, free calls) is somewhat promotional yet operationally relevant, so it mostly earns its place.

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 return-value burden and does so well: it lists the 8 scored kootas, per-koota attributes/rules, dosha flags with cancellations, Manglik status, and the sha256 hash. It is complete enough to call correctly, though the options object and any result shape details remain unspecified.

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 67% and nested objects are documented in the schema itself (the person_a/person_b descriptions already state groom/boy and bride/girl). The description largely restates that convention and says nothing about the 'options' object (ayanamsa, node_type, house_system), so it adds little beyond the structured fields. 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?

Names a specific technique (36-point Ashtakoota marriage compatibility) and enumerates the exact outputs: all 8 kootas with reasons, dosha flags, cancellations, and Manglik status for both partners. This clearly distinguishes it from siblings like kundli (individual chart) and synastry (a different compatibility system).

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 supplies the crucial convention that boy = person_a and girl = person_b, plus pricing/free-call context, which helps an agent invoke it correctly. However it never states when to prefer this over the sibling 'synastry' or 'kundli' tools, so routing is left to inference from the name.

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