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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds real context beyond that, namely the POST /v1/horary endpoint and the 20-credit Tier 2 cost, which is useful for budgeting calls, but it says nothing about latency, caching, or failure modes.

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 prose sentence is front-loaded and the bracketed metadata block is compact, scannable, and carries cost and endpoint facts that are not available in structured fields. Slightly bulky formatting but no redundant padding.

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?

For a 15-parameter tool with an output schema (so return values need no explanation), the definition covers the core purpose and cost but leaves the timezone-vs-timezoneOffset decision, house/zodiac selection, and sibling disambiguation to the schema alone. Adequate as a minimum viable description, not 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 only 33% across 15 parameters, so the description should compensate and does not. It merely restates the four required parameters (date, time, latitude, longitude) that the schema already marks as required, and adds no meaning for houseSystem, zodiacType, cosmogram, name, city, or the ayanamsa choices.

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?

States a specific verb and resource ('Calculate a horary chart') plus the outputs it yields ('radicality assessment and significator analysis'), which is more informative than the bare name. It does not, however, distinguish this core horary calculation from the five sibling horary tools (diagnostics, moon_aspects, moon_voc, planetary_hours, via_combusta) or from astroway_vedic_kp_horary.

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?

There is no when-to-use guidance and no mention of alternatives, despite several closely related horary siblings. The only routing help is the required-parameter list and cost tag; an agent still has to guess whether this is the base chart call or one of the specialized horary endpoints.

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