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

Beyond the annotations (readOnlyHint, idempotentHint, destructiveHint=false), the description adds critical behavioral traits: 'Read-only deterministic computation (Swiss Ephemeris, Lahiri ayanamsa); no writes, no auth, at least 30 requests/min/IP per server instance, plus a shared engine budget of at least 60/min/IP across all engine-backed tools.' It also clarifies that Nadi/bhakoot dosha is chart-pair compatibility, not individual Mars dosha. No contradiction with 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?

The description is concise yet comprehensive, with no wasted sentences. It front-loads the core purpose and then efficiently covers usage, behavioral traits, parameter context, and return values. Each sentence provides distinct value, achieving an excellent balance of detail and brevity.

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?

Given the absence of an output schema, the description thoroughly explains the return structure: 'each of the eight koots... with points earned out of its maximum, the total out of 36, any koot-level dosha, the classical cancellation that applies to it if one does, and an overall verdict.' It also specifies prerequisites (exact birth time and place). This provides complete context for an agent to understand what the tool does and what it returns.

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% with detailed descriptions for each parameter. The description adds semantic value by explaining why gender is required ('several koots are scored asymmetrically') and the necessity of exact birth time ('the ascendant moves about one degree every four minutes'). It also enriches understanding by outlining what the tool returns (eight koots, points, totals, dosha, cancellation, verdict).

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?

Clearly states the verb 'Returns' and the resource 'classical Ashtakoot marriage compatibility (kundli milan / gun milan) between two people from both birth charts'. It explicitly differentiates from sibling tool 'get_love_compatibility', ensuring the agent selects the correct tool for real marriage matching.

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?

Provides explicit guidance: 'Use this whenever real marriage matching is asked for.' Directly contrasts with 'get_love_compatibility' which is 'name-numerology entertainment and is NOT a substitute.' Also advises to call 'check_manglik' for individual Mars dosha, covering when not to use this tool.

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