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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is low. The description adds genuine context beyond them: the cost tier (50 credits, Tier 3) and the shape of the verdict output including Bhakoot/Nadi dosha flags. It does not mention auth requirements or latency, but for a pure read-only computation 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?

Front-loaded with the defining content (8-Kuta breakdown, thresholds, return shape) before the bracketed metadata, so an agent gets the essentials in the first sentence. The Kuta enumeration is dense but each item earns its place as a scope definition; the [Required] line is mildly redundant with the schema.

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 a full output schema, rich annotations, and 100% parameter description coverage in the schema, the description need not explain returns or chart construction. It supplies the domain framing (what the 36-point scale means, what the dosha flags are) that lets an agent report results sensibly. Only the absence of sibling routing keeps it from being fully complete.

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 the schema already documents every parameter, including the compact-mode `fields` and `precision` options and the rich chart object semantics. The description only restates the two required params (chart1, chart2), adding nothing the schema does not already carry. Baseline 3 is correct.

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 resource and scope precisely: the canonical 8-Kuta / 36-point matchmaking, enumerating all eight Kutas with their weights (Varna 1 through Nadi 8). That enumeration uniquely identifies it against siblings like astroway_vedic_compatibility_dashakoota (10-Kuta) or _full, even though no sibling is named outright. Clear and specific, but it stops short of explicit sibling routing.

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?

The threshold bands (18+ acceptable, 24+ good, 32+ excellent) are interpretation guidance for reading the result, not invocation guidance. There is no statement of when to choose this over the other four compatibility endpoints (bhrigu_match, dashakoota, full, mangal_match) or any prerequisite for calling it. Usage is implied by the name only.

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