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 lower. The description adds one genuinely useful non-schema behavior: a cost of 20 credits (Tier 2). It says nothing about limits or what the response contains, so 3 is appropriate.

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 tightly packed fragments with no filler, and the chart identity is front-loaded. Slightly telegraphic, but every element carries information.

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?

An output schema exists, so return values need not be described, but for a 15-parameter tool with 33% coverage the description should at least signal timezone/location handling or when to prefer D9. It leaves real gaps that the schema alone does not close.

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 only 33% across 15 parameters, and the description adds no parameter meaning at all. Required fields like date/time/latitude/longitude rely purely on patterns and types, and the description does nothing to compensate for the undocumented params.

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 chart artifact (the Navamsa / D9 divisional chart) and its significations (spouse, dharma), which lets an agent distinguish it from the ~20 sibling varga tools indexed by division number. It does not explicitly say 'compute/generate', but the resource is unambiguous.

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 'spouse, dharma' parenthetical implies the domain of use, but there is no explicit statement of when to select D9 over D1/D10/D60 or what prerequisites apply. Usage is inferable but not spelled out, and no alternative is named.

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